diff --git a/databases/core.py b/databases/core.py
index 8394ab5c..981e3c47 100644
--- a/databases/core.py
+++ b/databases/core.py
@@ -7,6 +7,7 @@
 from types import TracebackType
 from urllib.parse import SplitResult, parse_qsl, unquote, urlsplit
 
+from pymysql.err import OperationalError
 from sqlalchemy import text
 from sqlalchemy.sql import ClauseElement
 
@@ -391,25 +392,37 @@ async def start(self) -> "Transaction":
         async with self._connection._transaction_lock:
             is_root = not self._connection._transaction_stack
             await self._connection.__aenter__()
-            await self._transaction.start(
-                is_root=is_root, extra_options=self._extra_options
-            )
-            self._connection._transaction_stack.append(self)
+            try:
+                await self._transaction.start(
+                    is_root=is_root, extra_options=self._extra_options
+                )
+                self._connection._transaction_stack.append(self)
+            except Exception as e:
+                await self._connection.__aexit__()
+                raise e
         return self
 
     async def commit(self) -> None:
         async with self._connection._transaction_lock:
             assert self._connection._transaction_stack[-1] is self
             self._connection._transaction_stack.pop()
-            await self._transaction.commit()
-            await self._connection.__aexit__()
+            try:
+                await self._transaction.commit()
+            except Exception as e:
+                raise e
+            finally:
+                await self._connection.__aexit__()
 
     async def rollback(self) -> None:
         async with self._connection._transaction_lock:
             assert self._connection._transaction_stack[-1] is self
             self._connection._transaction_stack.pop()
-            await self._transaction.rollback()
-            await self._connection.__aexit__()
+            try:
+                await self._transaction.rollback()
+            except Exception as e:
+                raise e
+            finally:
+                await self._connection.__aexit__()
 
 
 class _EmptyNetloc(str):
diff --git a/requirements.txt b/requirements.txt
index 0699d3cc..1394fcc8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -20,6 +20,7 @@ pytest==7.1.2
 pytest-cov==3.0.0
 starlette==0.20.4
 requests==2.28.1
+types-PyMySQL==1.0.19.1
 
 # Documentation
 mkdocs==1.3.1
@@ -29,3 +30,4 @@ mkautodoc==0.1.0
 # Packaging
 twine==4.0.1
 wheel==0.38.1
+