diff --git a/dvc/repo/ls.py b/dvc/repo/ls.py
index e02d52116a..2222decf27 100644
--- a/dvc/repo/ls.py
+++ b/dvc/repo/ls.py
@@ -76,9 +76,9 @@ def onerror(exc):
             if not recursive:
                 for dname in dirs:
                     info = PathInfo(root) / dname
-                    if not dvc_only or (
-                        tree.dvctree and tree.dvctree.exists(info)
-                    ):
+                    # pylint:disable=protected-access
+                    _, dvctree = tree._get_tree_pairs(info)  # noqa
+                    if not dvc_only or (dvctree and dvctree.exists(info)):
                         dvc = tree.isdvc(info)
                         path = str(info.relative_to(path_info))
                         ret[path] = {
diff --git a/dvc/repo/tree.py b/dvc/repo/tree.py
index 8011d0318c..9140c6fa71 100644
--- a/dvc/repo/tree.py
+++ b/dvc/repo/tree.py
@@ -1,5 +1,11 @@
 import logging
 import os
+import threading
+from itertools import takewhile
+from typing import Optional, Tuple
+
+from funcy import wrap_with
+from pygtrie import StringTrie
 
 from dvc.dvcfile import is_valid_filename
 from dvc.exceptions import OutputNotFoundError
@@ -248,25 +254,82 @@ class RepoTree(BaseTree):  # pylint:disable=abstract-method
     scheme = "local"
     PARAM_CHECKSUM = "md5"
 
-    def __init__(self, repo, **kwargs):
+    def __init__(self, repo, subrepos=False, repo_factory=None, **kwargs):
         super().__init__(repo, {"url": repo.root_dir})
-        if hasattr(repo, "dvc_dir"):
-            self.dvctree = DvcTree(repo, **kwargs)
+
+        if not repo_factory:
+            from dvc.repo import Repo
+
+            self.repo_factory = Repo
         else:
-            # git-only erepo's do not need dvctree
-            self.dvctree = None
+            self.repo_factory = repo_factory
+
+        self._main_repo = repo
+        self.root_dir = repo.root_dir
+        self._traverse_subrepos = subrepos
+
+        self._discovered_subrepos = StringTrie(separator=os.sep)
+        self._discovered_subrepos[self.root_dir] = repo
+
+        self._dvctrees = {}
+        self._dvctree_configs = kwargs
+
+        if hasattr(repo, "dvc_dir"):
+            self._dvctrees[repo.root_dir] = DvcTree(repo, **kwargs)
+
+    def _get_repo(self, path):
+        repo = self._discovered_subrepos.get(path)
+        if repo:
+            return repo
+
+        prefix, repo = self._discovered_subrepos.longest_prefix(path)
+        if not prefix:
+            return None
+
+        parents = (parent.fspath for parent in PathInfo(path).parents)
+        dirs = [path] + list(takewhile(lambda p: p != prefix, parents))
+        dirs.reverse()
+        self._update(dirs, starting_repo=repo)
+        return self._discovered_subrepos.get(path)
+
+    @wrap_with(threading.Lock())
+    def _update(self, dirs, starting_repo):
+        repo = starting_repo
+        for d in dirs:
+            if self._is_dvc_repo(d):
+                repo = self.repo_factory(d)
+                self._dvctrees[repo.root_dir] = DvcTree(
+                    repo, **self._dvctree_configs
+                )
+            self._discovered_subrepos[d] = repo
+
+    def _is_dvc_repo(self, dir_path):
+        if not self._traverse_subrepos:
+            return False
+
+        from dvc.repo import Repo
+
+        repo_path = os.path.join(dir_path, Repo.DVC_DIR)
+        return self._main_repo.tree.isdir(repo_path, use_dvcignore=False)
+
+    def _get_tree_pairs(self, path) -> Tuple["BaseTree", Optional["DvcTree"]]:
+        path = os.path.abspath(path)
+        repo = self._get_repo(path)
+        if not repo:
+            # path could be outside of the repo, so we just send them the main
+            # tree instead
+            return self._main_repo.tree, self._dvctrees.get(self.root_dir)
+
+        dvc_tree = self._dvctrees.get(repo.root_dir)
+        return repo.tree, dvc_tree
 
     @property
     def fetch(self):
-        if self.dvctree:
-            return self.dvctree.fetch
-        return False
+        return "fetch" in self._dvctree_configs
 
     @property
     def stream(self):
-        if self.dvctree:
-            return self.dvctree.stream
-        return False
+        return "stream" in self._dvctree_configs
 
     def open(
         self, path, mode="r", encoding="utf-8", **kwargs
@@ -274,52 +337,65 @@ def open(
         if "b" in mode:
             encoding = None
 
-        if self.dvctree and self.dvctree.exists(path):
-            return self.dvctree.open(
-                path, mode=mode, encoding=encoding, **kwargs
-            )
-        return self.repo.tree.open(path, mode=mode, encoding=encoding)
+        tree, dvc_tree = self._get_tree_pairs(path)
+        if dvc_tree and dvc_tree.exists(path):
+            return dvc_tree.open(path, mode=mode, encoding=encoding, **kwargs)
+        return tree.open(path, mode=mode, encoding=encoding)
 
     def exists(
         self, path, use_dvcignore=True
     ):  # pylint: disable=arguments-differ
-        return self.repo.tree.exists(path) or (
-            self.dvctree and self.dvctree.exists(path)
-        )
+        tree, dvc_tree = self._get_tree_pairs(path)
+        return tree.exists(path) or (dvc_tree and dvc_tree.exists(path))
 
     def isdir(self, path):  # pylint: disable=arguments-differ
-        return self.repo.tree.isdir(path) or (
-            self.dvctree and self.dvctree.isdir(path)
-        )
+        tree, dvc_tree = self._get_tree_pairs(path)
+        return tree.isdir(path) or (dvc_tree and dvc_tree.isdir(path))
 
     def isdvc(self, path, **kwargs):
-        return self.dvctree is not None and self.dvctree.isdvc(path, **kwargs)
+        _, dvc_tree = self._get_tree_pairs(path)
+        return dvc_tree is not None and dvc_tree.isdvc(path, **kwargs)
 
     def isfile(self, path):  # pylint: disable=arguments-differ
-        return self.repo.tree.isfile(path) or (
-            self.dvctree and self.dvctree.isfile(path)
-        )
+        tree, dvc_tree = self._get_tree_pairs(path)
+        return tree.isfile(path) or (dvc_tree and dvc_tree.isfile(path))
 
     def isexec(self, path):
-        if self.dvctree and self.dvctree.exists(path):
-            return self.dvctree.isexec(path)
-        return self.repo.tree.isexec(path)
+        tree, dvc_tree = self._get_tree_pairs(path)
+        if dvc_tree and dvc_tree.exists(path):
+            return dvc_tree.isexec(path)
+        return tree.isexec(path)
 
     def stat(self, path):
-        return self.repo.tree.stat(path)
+        tree, _ = self._get_tree_pairs(path)
+        return tree.stat(path)
 
-    def _walk_one(self, walk):
+    def _dvc_walk(self, walk):
         try:
             root, dirs, files = next(walk)
         except StopIteration:
             return
         yield root, dirs, files
         for _ in dirs:
-            yield from self._walk_one(walk)
+            yield from self._dvc_walk(walk)
+
+    def _subrepo_walk(self, dir_path, **kwargs):
+        tree, dvc_tree = self._get_tree_pairs(dir_path)
+        tree_walk = tree.walk(
+            dir_path, topdown=True, ignore_subrepos=not self._traverse_subrepos
+        )
+        if dvc_tree:
+            dvc_walk = dvc_tree.walk(dir_path, topdown=True, **kwargs)
+        else:
+            dvc_walk = None
+        yield from self._walk(tree_walk, dvc_walk, **kwargs)
 
-    def _walk(self, dvc_walk, repo_walk, dvcfiles=False):
+    def _walk(self, repo_walk, dvc_walk=None, dvcfiles=False):
+        assert repo_walk
         try:
-            _, dvc_dirs, dvc_fnames = next(dvc_walk)
+            _, dvc_dirs, dvc_fnames = (
+                next(dvc_walk) if dvc_walk else (None, [], [])
+            )
             repo_root, repo_dirs, repo_fnames = next(repo_walk)
         except StopIteration:
             return
@@ -347,12 +423,15 @@ def _walk(self, dvc_walk, repo_walk, dvcfiles=False):
         repo_dirs[:] = [dirname for dirname in dirs if dirname in repo_set]
 
         for dirname in dirs:
-            if dirname in shared:
-                yield from self._walk(dvc_walk, repo_walk, dvcfiles=dvcfiles)
+            dir_path = os.path.join(repo_root, dirname)
+            if self._is_dvc_repo(dir_path):
+                yield from self._subrepo_walk(dir_path, dvcfiles=dvcfiles)
+            elif dirname in shared:
+                yield from self._walk(repo_walk, dvc_walk, dvcfiles=dvcfiles)
             elif dirname in dvc_set:
-                yield from self._walk_one(dvc_walk)
+                yield from self._dvc_walk(dvc_walk)
             elif dirname in repo_set:
-                yield from self._walk_one(repo_walk)
+                yield from self._walk(repo_walk, None, dvcfiles=dvcfiles)
 
     def walk(
         self, top, topdown=True, onerror=None, dvcfiles=False, **kwargs
@@ -382,22 +461,28 @@ def walk(
                 onerror(NotADirectoryError(top))
             return
 
-        dvc_exists = self.dvctree and self.dvctree.exists(top)
-        repo_exists = self.repo.tree.exists(top)
-        if dvc_exists and not repo_exists:
-            yield from self.dvctree.walk(
-                top, topdown=topdown, onerror=onerror, **kwargs
-            )
-            return
-        if repo_exists and not dvc_exists:
-            yield from self.repo.tree.walk(
-                top, topdown=topdown, onerror=onerror
+        tree, dvc_tree = self._get_tree_pairs(top)
+        dvc_exists = dvc_tree and dvc_tree.exists(top)
+        repo_exists = tree.exists(top)
+        if dvc_exists:
+            dvc_walk = dvc_tree.walk(top, topdown=topdown, **kwargs)
+            if repo_exists:
+                repo_walk = tree.walk(
+                    top,
+                    topdown=topdown,
+                    ignore_subrepos=not self._traverse_subrepos,
+                )
+                yield from self._walk(repo_walk, dvc_walk, dvcfiles=dvcfiles)
+            else:
+                yield from dvc_walk
+        else:
+            repo_walk = tree.walk(
+                top,
+                topdown=topdown,
+                onerror=onerror,
+                ignore_subrepos=not self._traverse_subrepos,
             )
-            return
-
-        dvc_walk = self.dvctree.walk(top, topdown=topdown, **kwargs)
-        repo_walk = self.repo.tree.walk(top, topdown=topdown)
-        yield from self._walk(dvc_walk, repo_walk, dvcfiles=dvcfiles)
+            yield from self._walk(repo_walk, None, dvcfiles=dvcfiles)
 
     def walk_files(self, top, **kwargs):  # pylint: disable=arguments-differ
         for root, _, files in self.walk(top, **kwargs):
@@ -413,9 +498,10 @@ def get_file_hash(self, path_info):
         """
         if not self.exists(path_info):
             raise FileNotFoundError
-        if self.dvctree and self.dvctree.exists(path_info):
+        _, dvc_tree = self._get_tree_pairs(path_info)
+        if dvc_tree and dvc_tree.exists(path_info):
             try:
-                return self.dvctree.get_file_hash(path_info)
+                return dvc_tree.get_file_hash(path_info)
             except OutputNotFoundError:
                 pass
         return file_md5(path_info, self)[0]
@@ -444,4 +530,4 @@ def copytree(self, top, dest):
 
     @property
     def hash_jobs(self):  # pylint: disable=invalid-overridden-method
-        return self.repo.tree.hash_jobs
+        return self._main_repo.tree.hash_jobs
diff --git a/dvc/tree/git.py b/dvc/tree/git.py
index e4f2548982..066f77be6d 100644
--- a/dvc/tree/git.py
+++ b/dvc/tree/git.py
@@ -240,3 +240,6 @@ def walk_files(self, top):  # pylint: disable=arguments-differ
             for file in files:
                 # NOTE: os.path.join is ~5.5 times slower
                 yield f"{root}{os.sep}{file}"
+
+    def _reset(self):
+        return self.__dict__.pop("dvcignore", None)
diff --git a/dvc/tree/local.py b/dvc/tree/local.py
index ca3b8cfbfe..994277aea3 100644
--- a/dvc/tree/local.py
+++ b/dvc/tree/local.py
@@ -357,3 +357,6 @@ def _remove_unpacked_dir(self, hash_):
         info = self.hash_to_path_info(hash_)
         path_info = info.with_name(info.name + self.UNPACKED_DIR_SUFFIX)
         self.remove(path_info)
+
+    def _reset(self):
+        return self.__dict__.pop("dvcignore", None)
diff --git a/tests/func/test_ignore.py b/tests/func/test_ignore.py
index 042329f79c..86937234e1 100644
--- a/tests/func/test_ignore.py
+++ b/tests/func/test_ignore.py
@@ -21,7 +21,7 @@ def test_ignore(tmp_dir, dvc, monkeypatch):
     tmp_dir.gen({"dir": {"ignored": "text", "other": "text2"}})
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "dir/ignored")
 
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     path = PathInfo(tmp_dir)
 
@@ -31,7 +31,7 @@ def test_ignore(tmp_dir, dvc, monkeypatch):
 def test_ignore_unicode(tmp_dir, dvc):
     tmp_dir.gen({"dir": {"other": "text", "тест": "проверка"}})
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "dir/тест")
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {path / "dir" / "other"}
 
@@ -40,7 +40,7 @@ def test_rename_ignored_file(tmp_dir, dvc):
     tmp_dir.gen({"dir": {"ignored": "...", "other": "text"}})
 
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "ignored*")
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     mtime, size = get_mtime_and_size("dir", dvc.tree)
 
@@ -63,7 +63,7 @@ def test_rename_file(tmp_dir, dvc):
 def test_remove_ignored_file(tmp_dir, dvc):
     tmp_dir.gen({"dir": {"ignored": "...", "other": "text"}})
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "dir/ignored")
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     mtime, size = get_mtime_and_size("dir", dvc.tree)
 
@@ -96,7 +96,7 @@ def test_ignore_collecting_dvcignores(tmp_dir, dvc, dname):
 
     top_ignore_file = (tmp_dir / dname).with_name(DvcIgnore.DVCIGNORE_FILE)
     top_ignore_file.write_text(os.path.basename(dname))
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     ignore_file = tmp_dir / dname / DvcIgnore.DVCIGNORE_FILE
     ignore_file.write_text("foo")
@@ -127,7 +127,7 @@ def test_ignore_on_branch(tmp_dir, scm, dvc):
     with tmp_dir.branch("branch", new=True):
         tmp_dir.scm_gen(DvcIgnore.DVCIGNORE_FILE, "foo", commit="add ignore")
 
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path)) == {
         path / "foo",
@@ -150,7 +150,7 @@ def test_match_nested(tmp_dir, dvc):
             "dir": {"x.backup": "x backup", "tmp": "content"},
         }
     )
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     result = {os.fspath(os.path.normpath(f)) for f in dvc.tree.walk_files(".")}
     assert result == {".dvcignore", "foo"}
 
@@ -168,7 +168,7 @@ def test_ignore_subrepo(tmp_dir, scm, dvc):
     tmp_dir.gen({".dvcignore": "foo", "subdir": {"foo": "foo"}})
     scm.add([".dvcignore"])
     scm.commit("init parent dvcignore")
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     subrepo_dir = tmp_dir / "subdir"
     assert not dvc.tree.exists(PathInfo(subrepo_dir / "foo"))
@@ -189,7 +189,7 @@ def test_ignore_resurface_subrepo(tmp_dir, scm, dvc):
     with subrepo_dir.chdir():
         Repo.init(subdir=True)
 
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     dirs = ["subdir"]
     files = ["foo"]
@@ -207,7 +207,7 @@ def test_ignore_resurface_subrepo(tmp_dir, scm, dvc):
 def test_ignore_blank_line(tmp_dir, dvc):
     tmp_dir.gen({"dir": {"ignored": "text", "other": "text2"}})
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "foo\n\ndir/ignored")
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {path / "dir" / "other"}
 
@@ -242,7 +242,7 @@ def test_ignore_file_in_parent_path(
 ):
     tmp_dir.gen(data_struct)
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "\n".join(pattern_list))
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {
         path / relpath for relpath in result_set
@@ -265,7 +265,7 @@ def test_ignore_sub_directory(tmp_dir, dvc):
     )
     tmp_dir.gen({"dir": {DvcIgnore.DVCIGNORE_FILE: "doc/fortz"}})
 
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {
         path / "dir" / "a" / "doc" / "fortz" / "a",
@@ -277,7 +277,7 @@ def test_ignore_sub_directory(tmp_dir, dvc):
 def test_ignore_directory(tmp_dir, dvc):
     tmp_dir.gen({"dir": {"fortz": {}, "a": {"fortz": {}}}})
     tmp_dir.gen({"dir": {DvcIgnore.DVCIGNORE_FILE: "fortz"}})
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {
         path / "dir" / DvcIgnore.DVCIGNORE_FILE,
@@ -288,7 +288,7 @@ def test_multi_ignore_file(tmp_dir, dvc, monkeypatch):
     tmp_dir.gen({"dir": {"subdir": {"should_ignore": "1", "not_ignore": "1"}}})
     tmp_dir.gen(DvcIgnore.DVCIGNORE_FILE, "dir/subdir/*_ignore")
     tmp_dir.gen({"dir": {DvcIgnore.DVCIGNORE_FILE: "!subdir/not_ignore"}})
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     path = PathInfo(tmp_dir)
     assert set(dvc.tree.walk_files(path / "dir")) == {
         path / "dir" / "subdir" / "not_ignore",
@@ -313,7 +313,7 @@ def test_pattern_trie_tree(tmp_dir, dvc):
             "other": {DvcIgnore.DVCIGNORE_FILE: "1\n2\n3"},
         }
     )
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
     dvcignore = dvc.tree.dvcignore
 
     ignore_pattern_top = dvcignore._get_trie_pattern(
@@ -381,7 +381,7 @@ def test_ignore_in_added_dir(tmp_dir, dvc):
             ".dvcignore": "**/ignored",
         }
     )
-    dvc.tree.__dict__.pop("dvcignore", None)
+    dvc.tree._reset()
 
     ignored_path = tmp_dir / "dir" / "sub" / "ignored"
     assert not dvc.tree.exists(PathInfo(ignored_path))
diff --git a/tests/func/test_tree.py b/tests/func/test_tree.py
index a53a515a2e..7f90196beb 100644
--- a/tests/func/test_tree.py
+++ b/tests/func/test_tree.py
@@ -258,7 +258,7 @@ def test_walk_dont_ignore_subrepos(tmp_dir, scm, dvc):
     scm.commit("Add subrepo")
 
     dvc_tree = dvc.tree
-    dvc_tree.__dict__.pop("dvcignore")
+    dvc_tree._reset()
     scm_tree = scm.get_tree("HEAD", use_dvcignore=True)
     path = os.fspath(tmp_dir)
     get_dirs = itemgetter(1)
diff --git a/tests/unit/repo/test_repo_tree.py b/tests/unit/repo/test_repo_tree.py
index 417b2c0b92..9a4d5112c1 100644
--- a/tests/unit/repo/test_repo_tree.py
+++ b/tests/unit/repo/test_repo_tree.py
@@ -1,5 +1,6 @@
 import os
 import shutil
+from unittest import mock
 
 import pytest
 
@@ -177,3 +178,181 @@ def test_isdvc(tmp_dir, dvc):
     assert tree.isdvc("dir")
     assert not tree.isdvc("dir/baz")
     assert tree.isdvc("dir/baz", recursive=True, strict=False)
+
+
+def make_subrepo(dir_, scm, config=None):
+    dir_.mkdir(parents=True)
+    with dir_.chdir():
+        dir_.scm = scm
+        dir_.init(dvc=True, subdir=True)
+        if config:
+            dir_.add_remote(config=config)
+
+
+def test_subrepos(tmp_dir, scm, dvc):
+    tmp_dir.scm_gen(
+        {"dir": {"repo.txt": "file to confuse RepoTree"}},
+        commit="dir/repo.txt",
+    )
+
+    subrepo1 = tmp_dir / "dir" / "repo"
+    subrepo2 = tmp_dir / "dir" / "repo2"
+
+    for repo in [subrepo1, subrepo2]:
+        make_subrepo(repo, scm)
+
+    subrepo1.dvc_gen({"foo": "foo", "dir1": {"bar": "bar"}}, commit="FOO")
+    subrepo2.dvc_gen(
+        {"lorem": "lorem", "dir2": {"ipsum": "ipsum"}}, commit="BAR"
+    )
+
+    dvc.tree._reset()
+    tree = RepoTree(dvc, subrepos=True, fetch=True)
+
+    def assert_tree_belongs_to_repo(ret_val):
+        method = tree._get_repo
+
+        def f(*args, **kwargs):
+            r = method(*args, **kwargs)
+            assert r.root_dir == ret_val.root_dir
+            return r
+
+        return f
+
+    with mock.patch.object(
+        tree,
+        "_get_repo",
+        side_effect=assert_tree_belongs_to_repo(subrepo1.dvc),
+    ):
+        assert tree.exists(subrepo1 / "foo") is True
+        assert tree.exists(subrepo1 / "bar") is False
+
+        assert tree.isfile(subrepo1 / "foo") is True
+        assert tree.isfile(subrepo1 / "foo") is True
+        assert tree.isfile(subrepo1 / "dir1" / "bar") is True
+        assert tree.isfile(subrepo1 / "dir1") is False
+
+        assert tree.isdir(subrepo1 / "dir1") is True
+        assert tree.isdir(subrepo1 / "dir1" / "bar") is False
+        assert tree.isdvc(subrepo1 / "foo") is True
+
+    with mock.patch.object(
+        tree,
+        "_get_repo",
+        side_effect=assert_tree_belongs_to_repo(subrepo2.dvc),
+    ):
+        assert tree.exists(subrepo2 / "lorem") is True
+        assert tree.exists(subrepo2 / "ipsum") is False
+
+        assert tree.isfile(subrepo2 / "lorem") is True
+        assert tree.isfile(subrepo2 / "lorem") is True
+        assert tree.isfile(subrepo2 / "dir2" / "ipsum") is True
+        assert tree.isfile(subrepo2 / "dir2") is False
+
+        assert tree.isdir(subrepo2 / "dir2") is True
+        assert tree.isdir(subrepo2 / "dir2" / "ipsum") is False
+        assert tree.isdvc(subrepo2 / "lorem") is True
+
+
+@pytest.mark.parametrize(
+    "dvcfiles,extra_expected",
+    [
+        (False, []),
+        (
+            True,
+            [
+                PathInfo("dir") / "repo" / "foo.dvc",
+                PathInfo("dir") / "repo" / "dir1.dvc",
+                PathInfo("dir") / "repo2" / "lorem.dvc",
+                PathInfo("dir") / "repo2" / "dir2.dvc",
+            ],
+        ),
+    ],
+)
+def test_subrepo_walk(tmp_dir, scm, dvc, dvcfiles, extra_expected):
+    tmp_dir.scm_gen(
+        {"dir": {"repo.txt": "file to confuse RepoTree"}},
+        commit="dir/repo.txt",
+    )
+
+    subrepo1 = tmp_dir / "dir" / "repo"
+    subrepo2 = tmp_dir / "dir" / "repo2"
+
+    subdirs = [subrepo1, subrepo2]
+    for dir_ in subdirs:
+        make_subrepo(dir_, scm)
+
+    subrepo1.dvc_gen({"foo": "foo", "dir1": {"bar": "bar"}}, commit="FOO")
+    subrepo2.dvc_gen(
+        {"lorem": "lorem", "dir2": {"ipsum": "ipsum"}}, commit="BAR"
+    )
+
+    # using tree that does not have dvcignore
+    dvc.tree._reset()
+    tree = RepoTree(dvc, subrepos=True, fetch=True)
+    expected = [
+        PathInfo("dir") / "repo",
+        PathInfo("dir") / "repo.txt",
+        PathInfo("dir") / "repo2",
+        PathInfo("dir") / "repo" / ".gitignore",
+        PathInfo("dir") / "repo" / "foo",
+        PathInfo("dir") / "repo" / "dir1",
+        PathInfo("dir") / "repo" / "dir1" / "bar",
+        PathInfo("dir") / "repo2" / ".gitignore",
+        PathInfo("dir") / "repo2" / "lorem",
+        PathInfo("dir") / "repo2" / "dir2",
+        PathInfo("dir") / "repo2" / "dir2" / "ipsum",
+    ]
+
+    actual = []
+    for root, dirs, files in tree.walk("dir", dvcfiles=dvcfiles):
+        for entry in dirs + files:
+            actual.append(os.path.join(root, entry))
+
+    expected = [str(path) for path in expected + extra_expected]
+    assert set(actual) == set(expected)
+    assert len(actual) == len(expected)
+
+
+def test_repo_tree_no_subrepos(tmp_dir, dvc, scm):
+    tmp_dir.scm_gen(
+        {"dir": {"repo.txt": "file to confuse RepoTree"}},
+        commit="dir/repo.txt",
+    )
+    tmp_dir.dvc_gen({"lorem": "lorem"}, commit="add foo")
+
+    subrepo = tmp_dir / "dir" / "repo"
+    make_subrepo(subrepo, scm)
+    subrepo.dvc_gen({"foo": "foo", "dir1": {"bar": "bar"}}, commit="FOO")
+    subrepo.scm_gen({"ipsum": "ipsum"}, commit="BAR")
+
+    # using tree that does not have dvcignore
+    dvc.tree._reset()
+    tree = RepoTree(dvc, subrepos=False, fetch=True)
+    expected = [
+        tmp_dir / ".gitignore",
+        tmp_dir / "lorem",
+        tmp_dir / "lorem.dvc",
+        tmp_dir / "dir",
+        tmp_dir / "dir" / "repo.txt",
+    ]
+
+    actual = []
+    for root, dirs, files in tree.walk(tmp_dir, dvcfiles=True):
+        for entry in dirs + files:
+            actual.append(os.path.normpath(os.path.join(root, entry)))
+
+    expected = [str(path) for path in expected]
+    assert set(actual) == set(expected)
+    assert len(actual) == len(expected)
+
+    assert tree.isfile(tmp_dir / "lorem") is True
+    assert tree.isfile(tmp_dir / "dir" / "repo" / "foo") is False
+    assert tree.isdir(tmp_dir / "dir" / "repo") is False
+    assert tree.isdir(tmp_dir / "dir") is True
+
+    assert tree.isdvc(tmp_dir / "lorem") is True
+    assert tree.isdvc(tmp_dir / "dir" / "repo" / "dir1") is False
+
+    assert tree.exists(tmp_dir / "dir" / "repo.txt") is True
+    assert tree.exists(tmp_dir / "repo" / "ipsum") is False