diff --git a/tests/utils.py b/tests/utils.py
index 4b381e38..ca51fb6e 100644
--- a/tests/utils.py
+++ b/tests/utils.py
@@ -38,4 +38,6 @@ def flush_rethink_db(connection, dbname):
 
 @flush_db.register(MongoDBConnection)
 def flush_mongo_db(connection, dbname):
-    raise NotImplementedError
+    connection.conn[dbname].bigchain.delete_many({})
+    connection.conn[dbname].backlog.delete_many({})
+    connection.conn[dbname].votes.delete_many({})