diff --git a/moto/s3/models.py b/moto/s3/models.py
index 6098ad21c4d..e5955886469 100644
--- a/moto/s3/models.py
+++ b/moto/s3/models.py
@@ -1,3 +1,5 @@
+import os
+import base64
 import datetime
 import hashlib
 
@@ -5,6 +7,9 @@
 from moto.core.utils import iso_8601_datetime, rfc_1123_datetime
 from .utils import clean_key_name
 
+UPLOAD_ID_BYTES=43
+UPLOAD_PART_MIN_SIZE=5242880
+
 
 class FakeKey(object):
     def __init__(self, name, value):
@@ -23,7 +28,7 @@ def append_to_value(self, value):
     @property
     def etag(self):
         value_md5 = hashlib.md5()
-        value_md5.update(self.value)
+        value_md5.update(bytes(self.value))
         return '"{0}"'.format(value_md5.hexdigest())
 
     @property
@@ -52,10 +57,48 @@ def size(self):
         return len(self.value)
 
 
+class FakeMultipart(object):
+    def __init__(self, key_name):
+        self.key_name = key_name
+        self.parts = {}
+        self.id = base64.b64encode(os.urandom(UPLOAD_ID_BYTES)).replace('=', '').replace('+', '')
+
+    def complete(self):
+        total = bytearray()
+        last_part_name = len(self.list_parts())
+
+        for part in self.list_parts():
+            if part.name != last_part_name and len(part.value) < UPLOAD_PART_MIN_SIZE:
+                return
+            total.extend(part.value)
+
+        return total
+
+    def set_part(self, part_id, value):
+        if part_id < 1:
+            return
+
+        key = FakeKey(part_id, value)
+        self.parts[part_id] = key
+        return key
+
+    def list_parts(self):
+        parts = []
+
+        for part_id, index in enumerate(sorted(self.parts.keys()), start=1):
+            # Make sure part ids are continuous
+            if part_id != index:
+                return
+            parts.append(self.parts[part_id])
+
+        return parts
+
+
 class FakeBucket(object):
     def __init__(self, name):
         self.name = name
         self.keys = {}
+        self.multiparts = {}
 
 
 class S3Backend(BaseBackend):
@@ -106,6 +149,36 @@ def get_key(self, bucket_name, key_name):
         if bucket:
             return bucket.keys.get(key_name)
 
+    def initiate_multipart(self, bucket_name, key_name):
+        bucket = self.buckets[bucket_name]
+        new_multipart = FakeMultipart(key_name)
+        bucket.multiparts[new_multipart.id] = new_multipart
+
+        return new_multipart
+
+    def complete_multipart(self, bucket_name, multipart_id):
+        bucket = self.buckets[bucket_name]
+        multipart = bucket.multiparts[multipart_id]
+        value = multipart.complete()
+        if value is None:
+            return
+        del bucket.multiparts[multipart_id]
+
+        return self.set_key(bucket_name, multipart.key_name, value)
+
+    def cancel_multipart(self, bucket_name, multipart_id):
+        bucket = self.buckets[bucket_name]
+        del bucket.multiparts[multipart_id]
+
+    def list_multipart(self, bucket_name, multipart_id):
+        bucket = self.buckets[bucket_name]
+        return bucket.multiparts[multipart_id].list_parts()
+
+    def set_part(self, bucket_name, multipart_id, part_id, value):
+        bucket = self.buckets[bucket_name]
+        multipart = bucket.multiparts[multipart_id]
+        return multipart.set_part(part_id, value)
+
     def prefix_query(self, bucket, prefix, delimiter):
         key_results = set()
         folder_results = set()
diff --git a/moto/s3/responses.py b/moto/s3/responses.py
index 57a85fbfecd..d9b014206ab 100644
--- a/moto/s3/responses.py
+++ b/moto/s3/responses.py
@@ -116,6 +116,7 @@ def key_response(self, request, full_url, headers):
 
     def _key_response(self, request, full_url, headers):
         parsed_url = urlparse(full_url)
+        query = parse_qs(parsed_url.query)
         method = request.method
 
         key_name = self.parse_key_name(parsed_url.path)
@@ -130,6 +131,17 @@ def _key_response(self, request, full_url, headers):
             body = request.data
 
         if method == 'GET':
+            if 'uploadId' in query:
+                upload_id = query['uploadId'][0]
+                parts = self.backend.list_multipart(bucket_name, upload_id)
+                template = Template(S3_MULTIPART_LIST_RESPONSE)
+                return 200, headers, template.render(
+                    bucket_name=bucket_name,
+                    key_name=key_name,
+                    upload_id=upload_id,
+                    count=len(parts),
+                    parts=parts
+                    )
             key = self.backend.get_key(bucket_name, key_name)
             if key:
                 headers.update(key.metadata)
@@ -137,6 +149,14 @@ def _key_response(self, request, full_url, headers):
             else:
                 return 404, headers, ""
         if method == 'PUT':
+            if 'uploadId' in query and 'partNumber' in query and body:
+                upload_id = query['uploadId'][0]
+                part_number = int(query['partNumber'][0])
+                key = self.backend.set_part(bucket_name, upload_id, part_number, body)
+                template = Template(S3_MULTIPART_UPLOAD_RESPONSE)
+                headers.update(key.response_dict)
+                return 200, headers, template.render(part=key)
+
             if 'x-amz-copy-source' in request.headers:
                 # Copy key
                 src_bucket, src_key = request.headers.get("x-amz-copy-source").split("/", 1)
@@ -177,9 +197,39 @@ def _key_response(self, request, full_url, headers):
             else:
                 return 404, headers, ""
         elif method == 'DELETE':
+            if 'uploadId' in query:
+                upload_id = query['uploadId'][0]
+                self.backend.cancel_multipart(bucket_name, upload_id)
+                return 204, headers, ""
             removed_key = self.backend.delete_key(bucket_name, key_name)
             template = Template(S3_DELETE_OBJECT_SUCCESS)
             return 204, headers, template.render(bucket=removed_key)
+        elif method == 'POST':
+            if body == '' and parsed_url.query == 'uploads':
+                multipart = self.backend.initiate_multipart(bucket_name, key_name)
+                template = Template(S3_MULTIPART_INITIATE_RESPONSE)
+                response = template.render(
+                    bucket_name=bucket_name,
+                    key_name=key_name,
+                    upload_id=multipart.id,
+                )
+                return 200, headers, response
+
+            if 'uploadId' in query:
+                upload_id = query['uploadId'][0]
+                key = self.backend.complete_multipart(bucket_name, upload_id)
+
+                if key is not None:
+                    template = Template(S3_MULTIPART_COMPLETE_RESPONSE)
+                    return template.render(
+                        bucket_name=bucket_name,
+                        key_name=key.name,
+                        etag=key.etag,
+                    )
+                template = Template(S3_MULTIPART_COMPLETE_TOO_SMALL_ERROR)
+                return 400, headers, template.render()
+            else:
+                raise NotImplementedError("Method POST had only been implemented for multipart uploads so far")
         else:
             raise NotImplementedError("Method {0} has not been impelemented in the S3 backend yet".format(method))
 
@@ -279,3 +329,62 @@ def _key_response(self, request, full_url, headers):
     <LastModified>{{ key.last_modified_ISO8601 }}</LastModified>
   </CopyObjectResponse>
 </CopyObjectResponse>"""
+
+S3_MULTIPART_INITIATE_RESPONSE = """<?xml version="1.0" encoding="UTF-8"?>
+<InitiateMultipartUploadResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <Bucket>{{ bucket_name }}</Bucket>
+  <Key>{{ key_name }}</Key>
+  <UploadId>{{ upload_id }}</UploadId>
+</InitiateMultipartUploadResult>"""
+
+S3_MULTIPART_UPLOAD_RESPONSE = """<?xml version="1.0" encoding="UTF-8"?>
+<CopyPartResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <LastModified>{{ part.last_modified_ISO8601 }}</LastModified>
+  <ETag>{{ part.etag }}</ETag>
+</CopyPartResult>"""
+
+S3_MULTIPART_LIST_RESPONSE = """<?xml version="1.0" encoding="UTF-8"?>
+<ListPartsResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <Bucket>{{ bucket_name }}</Bucket>
+  <Key>{{ key_name }}</Key>
+  <UploadId>{{ upload_id }}</UploadId>
+  <StorageClass>STANDARD</StorageClass>
+  <Initiator>
+    <ID>75aa57f09aa0c8caeab4f8c24e99d10f8e7faeebf76c078efc7c6caea54ba06a</ID>
+    <DisplayName>webfile</DisplayName>
+  </Initiator>
+  <Owner>
+    <ID>75aa57f09aa0c8caeab4f8c24e99d10f8e7faeebf76c078efc7c6caea54ba06a</ID>
+    <DisplayName>webfile</DisplayName>
+  </Owner>
+  <StorageClass>STANDARD</StorageClass>
+  <PartNumberMarker>1</PartNumberMarker>
+  <NextPartNumberMarker>{{ count }} </NextPartNumberMarker>
+  <MaxParts>{{ count }}</MaxParts>
+  <IsTruncated>false</IsTruncated>
+  {% for part in parts %}
+  <Part>
+    <PartNumber>{{ part.name }}</PartNumber>
+    <LastModified>{{ part.last_modified_ISO8601 }}</LastModified>
+    <ETag>{{ part.etag }}</ETag>
+    <Size>{{ part.size }}</Size>
+  </Part>
+  {% endfor %}
+</ListPartsResult>"""
+
+S3_MULTIPART_COMPLETE_RESPONSE = """<?xml version="1.0" encoding="UTF-8"?>
+<CompleteMultipartUploadResult xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
+  <Location>http://{{ bucket_name }}.s3.amazonaws.com/{{ key_name }}</Location>
+  <Bucket>{{ bucket_name }}</Bucket>
+  <Key>{{ key_name }}</Key>
+  <ETag>{{ etag }}</ETag>
+</CompleteMultipartUploadResult>
+"""
+
+S3_MULTIPART_COMPLETE_TOO_SMALL_ERROR = """<?xml version="1.0" encoding="UTF-8"?>
+<Error>
+  <Code>EntityTooSmall</Code>
+  <Message>Your proposed upload is smaller than the minimum allowed object size.</Message>
+  <RequestId>asdfasdfsdafds</RequestId>
+  <HostId>sdfgdsfgdsfgdfsdsfgdfs</HostId>
+</Error>"""
diff --git a/tests/test_s3/test_s3.py b/tests/test_s3/test_s3.py
index 6b33f57605a..3d9e3f1fbf9 100644
--- a/tests/test_s3/test_s3.py
+++ b/tests/test_s3/test_s3.py
@@ -1,4 +1,5 @@
 import urllib2
+from io import BytesIO
 
 import boto
 from boto.exception import S3ResponseError
@@ -37,6 +38,34 @@ def test_my_model_save():
     conn.get_bucket('mybucket').get_key('steve').get_contents_as_string().should.equal('is awesome')
 
 
+@mock_s3
+def test_multipart_upload_too_small():
+    conn = boto.connect_s3('the_key', 'the_secret')
+    bucket = conn.create_bucket("foobar")
+
+    multipart = bucket.initiate_multipart_upload("the-key")
+    multipart.upload_part_from_file(BytesIO('hello'), 1)
+    multipart.upload_part_from_file(BytesIO('world'), 2)
+    # Multipart with total size under 5MB is refused
+    multipart.complete_upload.should.throw(S3ResponseError)
+
+
+@mock_s3
+def test_multipart_upload():
+    conn = boto.connect_s3('the_key', 'the_secret')
+    bucket = conn.create_bucket("foobar")
+
+    multipart = bucket.initiate_multipart_upload("the-key")
+    part1 = '0' * 5242880
+    multipart.upload_part_from_file(BytesIO(part1), 1)
+    # last part, can be less than 5 MB
+    part2 = '1'
+    multipart.upload_part_from_file(BytesIO(part2), 2)
+    multipart.complete_upload()
+    # we should get both parts as the key contents
+    bucket.get_key("the-key").get_contents_as_string().should.equal(part1 + part2)
+
+
 @mock_s3
 def test_missing_key():
     conn = boto.connect_s3('the_key', 'the_secret')