diff --git a/groot/gen.rboot.go b/groot/gen.rboot.go
index 7f5c4033d..e08a3483c 100644
--- a/groot/gen.rboot.go
+++ b/groot/gen.rboot.go
@@ -96,7 +96,7 @@ var (
 		"TLeafF", "TLeafD",
 		"TLeafF16", "TLeafD32",
 		"TLeafC",
-		"TNtuple",
+		"TNtuple", "TNtupleD",
 		"TTree",
 	}
 )
diff --git a/groot/rcmd/dump_test.go b/groot/rcmd/dump_test.go
index c70b9c43c..e7cfa28cd 100644
--- a/groot/rcmd/dump_test.go
+++ b/groot/rcmd/dump_test.go
@@ -52,6 +52,56 @@ func TestDump(t *testing.T) {
 [000][branch1.floatleaf]: 15.5
 [000][branch2.intleaf]: 20
 [000][branch2.floatleaf]: 781.2
+`,
+		},
+		{
+			name: "../testdata/tntuple.root",
+			want: `key[000]: ntup;1 "my ntuple title" (TNtuple)
+[000][x]: 0
+[000][y]: 0.5
+[001][x]: 1
+[001][y]: 1.5
+[002][x]: 2
+[002][y]: 2.5
+[003][x]: 3
+[003][y]: 3.5
+[004][x]: 4
+[004][y]: 4.5
+[005][x]: 5
+[005][y]: 5.5
+[006][x]: 6
+[006][y]: 6.5
+[007][x]: 7
+[007][y]: 7.5
+[008][x]: 8
+[008][y]: 8.5
+[009][x]: 9
+[009][y]: 9.5
+`,
+		},
+		{
+			name: "../testdata/tntupled.root",
+			want: `key[000]: ntup;1 "my ntuple title" (TNtupleD)
+[000][x]: 0
+[000][y]: 0.5
+[001][x]: 1
+[001][y]: 1.5
+[002][x]: 2
+[002][y]: 2.5
+[003][x]: 3
+[003][y]: 3.5
+[004][x]: 4
+[004][y]: 4.5
+[005][x]: 5
+[005][y]: 5.5
+[006][x]: 6
+[006][y]: 6.5
+[007][x]: 7
+[007][y]: 7.5
+[008][x]: 8
+[008][y]: 8.5
+[009][x]: 9
+[009][y]: 9.5
 `,
 		},
 		{
diff --git a/groot/rdict/cxx_root_streamers_gen.go b/groot/rdict/cxx_root_streamers_gen.go
index 9e60e349b..3f44a43e4 100644
--- a/groot/rdict/cxx_root_streamers_gen.go
+++ b/groot/rdict/cxx_root_streamers_gen.go
@@ -5268,6 +5268,34 @@ func init() {
 			Factor: 0.000000,
 		}.New()},
 	}))
+	StreamerInfos.Add(NewCxxStreamerInfo("TNtupleD", 1, 0x8de8d873, []rbytes.StreamerElement{
+		NewStreamerBase(Element{
+			Name:   *rbase.NewNamed("TTree", "Tree descriptor (the main ROOT I/O class)"),
+			Type:   rmeta.Base,
+			Size:   0,
+			ArrLen: 0,
+			ArrDim: 0,
+			MaxIdx: [5]int32{0, 1919213695, 0, 0, 0},
+			Offset: 0,
+			EName:  "BASE",
+			XMin:   0.000000,
+			XMax:   0.000000,
+			Factor: 0.000000,
+		}.New(), 20),
+		&StreamerBasicType{StreamerElement: Element{
+			Name:   *rbase.NewNamed("fNvar", "Number of columns"),
+			Type:   rmeta.Int,
+			Size:   4,
+			ArrLen: 0,
+			ArrDim: 0,
+			MaxIdx: [5]int32{0, 0, 0, 0, 0},
+			Offset: 0,
+			EName:  "int",
+			XMin:   0.000000,
+			XMax:   0.000000,
+			Factor: 0.000000,
+		}.New()},
+	}))
 	StreamerInfos.Add(NewCxxStreamerInfo("TTree", 20, 0x7264e07f, []rbytes.StreamerElement{
 		NewStreamerBase(Element{
 			Name:   *rbase.NewNamed("TNamed", "The basis for a named object (name, title)"),
diff --git a/groot/riofs/gendata/gen-tntuple.go b/groot/riofs/gendata/gen-tntuple.go
new file mode 100644
index 000000000..f85a6c6e3
--- /dev/null
+++ b/groot/riofs/gendata/gen-tntuple.go
@@ -0,0 +1,46 @@
+// Copyright ©2022 The go-hep Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"flag"
+	"log"
+
+	"go-hep.org/x/hep/groot/internal/rtests"
+)
+
+var (
+	root = flag.String("f", "test-tntuple.root", "output ROOT file")
+)
+
+func main() {
+	flag.Parse()
+
+	out, err := rtests.RunCxxROOT("gentntuple", []byte(script), *root)
+	if err != nil {
+		log.Fatalf("could not run ROOT macro:\noutput:\n%v\nerror: %+v", string(out), err)
+	}
+}
+
+const script = `
+void gentntuple(const char* fname) {
+	int bufsize = 32000;
+	int evtmax = 10;
+
+	auto f = TFile::Open(fname, "RECREATE");
+	auto t = new TNtuple("ntup", "my ntuple title", "x:y");
+
+	for (int i = 0; i != evtmax; i++) {
+		t->Fill(i, i+0.5);
+	}
+	f->Write();
+	f->Close();
+
+	exit(0);
+}
+`
diff --git a/groot/riofs/gendata/gen-tntupled.go b/groot/riofs/gendata/gen-tntupled.go
new file mode 100644
index 000000000..dbab7e23d
--- /dev/null
+++ b/groot/riofs/gendata/gen-tntupled.go
@@ -0,0 +1,46 @@
+// Copyright ©2022 The go-hep Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build ignore
+// +build ignore
+
+package main
+
+import (
+	"flag"
+	"log"
+
+	"go-hep.org/x/hep/groot/internal/rtests"
+)
+
+var (
+	root = flag.String("f", "test-tntupled.root", "output ROOT file")
+)
+
+func main() {
+	flag.Parse()
+
+	out, err := rtests.RunCxxROOT("gentntuple", []byte(script), *root)
+	if err != nil {
+		log.Fatalf("could not run ROOT macro:\noutput:\n%v\nerror: %+v", string(out), err)
+	}
+}
+
+const script = `
+void gentntuple(const char* fname) {
+	int bufsize = 32000;
+	int evtmax = 10;
+
+	auto f = TFile::Open(fname, "RECREATE");
+	auto t = new TNtupleD("ntup", "my ntuple title", "x:y");
+
+	for (int i = 0; i != evtmax; i++) {
+		t->Fill(i, i+0.5);
+	}
+	f->Write();
+	f->Close();
+
+	exit(0);
+}
+`
diff --git a/groot/riofs/riofs.go b/groot/riofs/riofs.go
index cf90a7cc3..9d94b9a32 100644
--- a/groot/riofs/riofs.go
+++ b/groot/riofs/riofs.go
@@ -26,6 +26,8 @@ import (
 //go:generate go run ./gendata/gen-tlv.go -f ../testdata/tlv-split00.root -split=0
 //go:generate go run ./gendata/gen-tlv.go -f ../testdata/tlv-split01.root -split=1
 //go:generate go run ./gendata/gen-tlv.go -f ../testdata/tlv-split99.root -split=99
+//go:generate go run ./gendata/gen-tntuple.go  -f ../testdata/tntuple.root
+//go:generate go run ./gendata/gen-tntupled.go -f ../testdata/tntupled.root
 
 // Directory describes a ROOT directory structure in memory.
 type Directory interface {
diff --git a/groot/rtree/reader.go b/groot/rtree/reader.go
index b940b718d..7f5625e1f 100644
--- a/groot/rtree/reader.go
+++ b/groot/rtree/reader.go
@@ -253,6 +253,10 @@ func newReader(t Tree, rvars []ReadVar, n int, beg, end int64) reader {
 	switch t := t.(type) {
 	case *ttree:
 		return newRTree(t, rvars, n, beg, end)
+	case *tntuple:
+		return newRTree(&t.ttree, rvars, n, beg, end)
+	case *tntupleD:
+		return newRTree(&t.ttree, rvars, n, beg, end)
 	case *chain:
 		return newRChain(t, rvars, n, beg, end)
 	case *join:
diff --git a/groot/rtree/tree.go b/groot/rtree/tree.go
index 71b12e17e..1783de409 100644
--- a/groot/rtree/tree.go
+++ b/groot/rtree/tree.go
@@ -646,6 +646,10 @@ type tntuple struct {
 	nvars int
 }
 
+func (*tntuple) RVersion() int16 {
+	return rvers.Ntuple
+}
+
 func (*tntuple) Class() string {
 	return "TNtuple"
 }
@@ -668,6 +672,37 @@ func (nt *tntuple) UnmarshalROOT(r *rbytes.RBuffer) error {
 	return r.Err()
 }
 
+type tntupleD struct {
+	ttree
+	nvars int
+}
+
+func (*tntupleD) RVersion() int16 {
+	return rvers.NtupleD
+}
+
+func (*tntupleD) Class() string {
+	return "TNtupleD"
+}
+
+func (nt *tntupleD) UnmarshalROOT(r *rbytes.RBuffer) error {
+	if r.Err() != nil {
+		return r.Err()
+	}
+
+	beg := r.Pos()
+	/*vers*/ _, pos, bcnt := r.ReadVersion(nt.Class())
+
+	if err := nt.ttree.UnmarshalROOT(r); err != nil {
+		return err
+	}
+
+	nt.nvars = int(r.ReadI32())
+
+	r.CheckByteCount(pos, bcnt, beg, nt.Class())
+	return r.Err()
+}
+
 type tioFeatures uint8
 
 func (*tioFeatures) Class() string { return "TIOFeatures" }
@@ -739,6 +774,13 @@ func init() {
 		}
 		rtypes.Factory.Add("TNtuple", f)
 	}
+	{
+		f := func() reflect.Value {
+			o := &tntupleD{}
+			return reflect.ValueOf(o)
+		}
+		rtypes.Factory.Add("TNtupleD", f)
+	}
 }
 
 var (
@@ -753,6 +795,11 @@ var (
 	_ Tree               = (*tntuple)(nil)
 	_ rbytes.Unmarshaler = (*tntuple)(nil)
 
+	_ root.Object        = (*tntupleD)(nil)
+	_ root.Named         = (*tntupleD)(nil)
+	_ Tree               = (*tntupleD)(nil)
+	_ rbytes.Unmarshaler = (*tntupleD)(nil)
+
 	_ root.Object        = (*tioFeatures)(nil)
 	_ rbytes.Marshaler   = (*tioFeatures)(nil)
 	_ rbytes.Unmarshaler = (*tioFeatures)(nil)
diff --git a/groot/rvers/versions_gen.go b/groot/rvers/versions_gen.go
index 8be41ee4b..e7533295d 100644
--- a/groot/rvers/versions_gen.go
+++ b/groot/rvers/versions_gen.go
@@ -104,5 +104,6 @@ const (
 	LeafD32                  = 1  // ROOT version for TLeafD32
 	LeafC                    = 1  // ROOT version for TLeafC
 	Ntuple                   = 2  // ROOT version for TNtuple
+	NtupleD                  = 1  // ROOT version for TNtupleD
 	Tree                     = 20 // ROOT version for TTree
 )
diff --git a/groot/testdata/tntuple.root b/groot/testdata/tntuple.root
new file mode 100644
index 000000000..dd9725667
Binary files /dev/null and b/groot/testdata/tntuple.root differ
diff --git a/groot/testdata/tntupled.root b/groot/testdata/tntupled.root
new file mode 100644
index 000000000..4987dc17d
Binary files /dev/null and b/groot/testdata/tntupled.root differ