diff --git a/moto/dynamodb2/responses.py b/moto/dynamodb2/responses.py
index cb716d563..03abf73c3 100644
--- a/moto/dynamodb2/responses.py
+++ b/moto/dynamodb2/responses.py
@@ -185,6 +185,10 @@ class DynamoHandler(BaseResponse):
         item = self.body['Item']
         return_values = self.body.get('ReturnValues', 'NONE')
 
+        if return_values not in ('ALL_OLD', 'NONE'):
+            er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
+            return self.error(er, 'Return values set to invalid value')
+
         if has_empty_keys_or_values(item):
             return get_empty_str_error()
 
@@ -524,7 +528,11 @@ class DynamoHandler(BaseResponse):
     def delete_item(self):
         name = self.body['TableName']
         keys = self.body['Key']
-        return_values = self.body.get('ReturnValues', '')
+        return_values = self.body.get('ReturnValues', 'NONE')
+        if return_values not in ('ALL_OLD', 'NONE'):
+            er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
+            return self.error(er, 'Return values set to invalid value')
+
         table = self.dynamodb_backend.get_table(name)
         if not table:
             er = 'com.amazonaws.dynamodb.v20120810#ConditionalCheckFailedException'
@@ -554,6 +562,11 @@ class DynamoHandler(BaseResponse):
         else:
             existing_attributes = {}
 
+        if return_values not in ('NONE', 'ALL_OLD', 'ALL_NEW', 'UPDATED_OLD',
+                                 'UPDATED_NEW'):
+            er = 'com.amazonaws.dynamodb.v20111205#ValidationException'
+            return self.error(er, 'Return values set to invalid value')
+
         if has_empty_keys_or_values(expression_attribute_values):
             return get_empty_str_error()
 
diff --git a/tests/test_dynamodb2/test_dynamodb.py b/tests/test_dynamodb2/test_dynamodb.py
index 5bfe8f9bd..47a714b1d 100644
--- a/tests/test_dynamodb2/test_dynamodb.py
+++ b/tests/test_dynamodb2/test_dynamodb.py
@@ -1000,6 +1000,11 @@ def test_delete_item():
     response = table.scan()
     assert response['Count'] == 2
 
+    # Test ReturnValues validation
+    with assert_raises(ClientError) as ex:
+        table.delete_item(Key={'client': 'client1', 'app': 'app1'},
+                          ReturnValues='ALL_NEW')
+    
     # Test deletion and returning old value
     response = table.delete_item(Key={'client': 'client1', 'app': 'app1'}, ReturnValues='ALL_OLD')
     response['Attributes'].should.contain('client')
@@ -1281,6 +1286,9 @@ def test_update_return_attributes():
     r = update('col1', 'val5', 'NONE')
     assert r['Attributes'] == {}
 
+    with assert_raises(ClientError) as ex:
+        r = update('col1', 'val6', 'WRONG')
+
 
 @mock_dynamodb2
 def test_put_return_attributes():
@@ -1306,7 +1314,16 @@ def test_put_return_attributes():
         ReturnValues='ALL_OLD'
     )
     assert r['Attributes'] == {'id': {'S': 'foo'}, 'col1': {'S': 'val1'}}
-    
+
+    with assert_raises(ClientError) as ex:
+        dynamodb.put_item(
+            TableName='moto-test',
+            Item={'id': {'S': 'foo'}, 'col1': {'S': 'val3'}},
+            ReturnValues='ALL_NEW'
+        )
+    ex.exception.response['Error']['Code'].should.equal('ValidationException')
+    ex.exception.response['ResponseMetadata']['HTTPStatusCode'].should.equal(400)
+    ex.exception.response['Error']['Message'].should.equal('Return values set to invalid value')
     
 
 @mock_dynamodb2