diff --git a/pywebpush/__init__.py b/pywebpush/__init__.py
index d834100..3312745 100644
--- a/pywebpush/__init__.py
+++ b/pywebpush/__init__.py
@@ -95,7 +95,7 @@ class WebPusher:
         "aes128gcm"  # draft-httpbis-encryption-encoding-04
     ]
 
-    def __init__(self, subscription_info):
+    def __init__(self, subscription_info, requests_session=None):
         """Initialize using the info provided by the client PushSubscription
         object (See
         https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe)
@@ -104,7 +104,16 @@ class WebPusher:
             the client.
         :type subscription_info: dict
 
+        :param requests_session: a requests.Session object to optimize requests
+            to the same client.
+        :type requests_session: requests.Session
+
         """
+        if requests_session is None:
+            self.requests_method = requests
+        else:
+            self.requests_method = requests_session
+
         if 'endpoint' not in subscription_info:
             raise WebPushException("subscription_info missing endpoint URL")
         self.subscription_info = subscription_info
@@ -285,10 +294,10 @@ class WebPusher:
         # Authorization / Crypto-Key (VAPID headers)
         if curl:
             return self.as_curl(endpoint, encoded_data, headers)
-        return requests.post(endpoint,
-                             data=encoded_data,
-                             headers=headers,
-                             timeout=timeout)
+        return self.requests_method.post(endpoint,
+                                         data=encoded_data,
+                                         headers=headers,
+                                         timeout=timeout)
 
 
 def webpush(subscription_info,
diff --git a/pywebpush/tests/test_webpush.py b/pywebpush/tests/test_webpush.py
index e70f681..136f749 100644
--- a/pywebpush/tests/test_webpush.py
+++ b/pywebpush/tests/test_webpush.py
@@ -318,3 +318,21 @@ class WebpushTestCase(unittest.TestCase):
         eq_(mock_post.call_args[1].get('timeout'), 5.2)
         webpush(subscription_info, timeout=10.001)
         eq_(mock_post.call_args[1].get('timeout'), 10.001)
+
+    @patch("requests.Session")
+    def test_send_using_requests_session(self, mock_session):
+        subscription_info = self._gen_subscription_info()
+        headers = {"Crypto-Key": "pre-existing",
+                   "Authentication": "bearer vapid"}
+        data = "Mary had a little lamb"
+        WebPusher(subscription_info,
+                  requests_session=mock_session).send(data, headers)
+        eq_(subscription_info.get('endpoint'),
+            mock_session.post.call_args[0][0])
+        pheaders = mock_session.post.call_args[1].get('headers')
+        eq_(pheaders.get('ttl'), '0')
+        ok_('encryption' in pheaders)
+        eq_(pheaders.get('AUTHENTICATION'), headers.get('Authentication'))
+        ckey = pheaders.get('crypto-key')
+        ok_('pre-existing' in ckey)
+        eq_(pheaders.get('content-encoding'), 'aesgcm')