1 files changed, 5 insertions, 2 deletions
diff --git a/lib/sqlalchemy/engine/base.py b/lib/sqlalchemy/engine/base.py
index 3cfe80081..04c14c2b7 100644
--- a/lib/sqlalchemy/engine/base.py
+++ b/lib/sqlalchemy/engine/base.py
@@ -1979,11 +1979,14 @@ class Transaction(object):
 
     def __exit__(self, type, value, traceback):
         if type is None and self.is_active:
-            self.commit()
+            try:
+                self.commit()
+            except:
+                self.rollback()
+                raise
         else:
             self.rollback()
 
-
 class RootTransaction(Transaction):
     def __init__(self, connection):
         super(RootTransaction, self).__init__(connection, None)