diff --git a/moto/rds/responses.py b/moto/rds/responses.py
index 0895a8bf2..987a6f21a 100644
--- a/moto/rds/responses.py
+++ b/moto/rds/responses.py
@@ -107,6 +107,9 @@ class RDSResponse(BaseResponse):
     def modify_db_instance(self):
         db_instance_identifier = self._get_param('DBInstanceIdentifier')
         db_kwargs = self._get_db_kwargs()
+        new_db_instance_identifier = self._get_param('NewDBInstanceIdentifier')
+        if new_db_instance_identifier:
+            db_kwargs['new_db_instance_identifier'] = new_db_instance_identifier
         database = self.backend.modify_database(
             db_instance_identifier, db_kwargs)
         template = self.response_template(MODIFY_DATABASE_TEMPLATE)
diff --git a/moto/rds2/models.py b/moto/rds2/models.py
index cca72efbd..268ae5af2 100644
--- a/moto/rds2/models.py
+++ b/moto/rds2/models.py
@@ -736,6 +736,10 @@ class RDS2Backend(BaseBackend):
 
     def modify_database(self, db_instance_identifier, db_kwargs):
         database = self.describe_databases(db_instance_identifier)[0]
+        if 'new_db_instance_identifier' in db_kwargs:
+            del self.databases[db_instance_identifier]
+            db_instance_identifier = db_kwargs['db_instance_identifier'] = db_kwargs.pop('new_db_instance_identifier')
+            self.databases[db_instance_identifier] = database
         database.update(db_kwargs)
         return database
 
diff --git a/moto/rds2/responses.py b/moto/rds2/responses.py
index bf76660aa..3e093221d 100644
--- a/moto/rds2/responses.py
+++ b/moto/rds2/responses.py
@@ -135,6 +135,9 @@ class RDS2Response(BaseResponse):
     def modify_db_instance(self):
         db_instance_identifier = self._get_param('DBInstanceIdentifier')
         db_kwargs = self._get_db_kwargs()
+        new_db_instance_identifier = self._get_param('NewDBInstanceIdentifier')
+        if new_db_instance_identifier:
+            db_kwargs['new_db_instance_identifier'] = new_db_instance_identifier
         database = self.backend.modify_database(
             db_instance_identifier, db_kwargs)
         template = self.response_template(MODIFY_DATABASE_TEMPLATE)
diff --git a/tests/test_rds2/test_rds2.py b/tests/test_rds2/test_rds2.py
index 47b5cf9f9..183a183b1 100644
--- a/tests/test_rds2/test_rds2.py
+++ b/tests/test_rds2/test_rds2.py
@@ -225,6 +225,28 @@ def test_modify_db_instance():
     instances['DBInstances'][0]['AllocatedStorage'].should.equal(20)
 
 
+@mock_rds2
+def test_rename_db_instance():
+    conn = boto3.client('rds', region_name='us-west-2')
+    database = conn.create_db_instance(DBInstanceIdentifier='db-master-1',
+                                       AllocatedStorage=10,
+                                       DBInstanceClass='postgres',
+                                       Engine='db.m1.small',
+                                       MasterUsername='root',
+                                       MasterUserPassword='hunter2',
+                                       Port=1234,
+                                       DBSecurityGroups=['my_sg'])
+    instances = conn.describe_db_instances(DBInstanceIdentifier="db-master-1")
+    list(instances['DBInstances']).should.have.length_of(1)
+    conn.describe_db_instances.when.called_with(DBInstanceIdentifier="db-master-2").should.throw(ClientError)
+    conn.modify_db_instance(DBInstanceIdentifier='db-master-1',
+                            NewDBInstanceIdentifier='db-master-2',
+                            ApplyImmediately=True)
+    conn.describe_db_instances.when.called_with(DBInstanceIdentifier="db-master-1").should.throw(ClientError)
+    instances = conn.describe_db_instances(DBInstanceIdentifier="db-master-2")
+    list(instances['DBInstances']).should.have.length_of(1)
+
+
 @mock_rds2
 def test_modify_non_existant_database():
     conn = boto3.client('rds', region_name='us-west-2')