diff -r 66d0f6ef2a7f Lib/test/test_urllib2net.py
--- a/Lib/test/test_urllib2net.py	Thu Feb 28 18:03:16 2013 +0200
+++ b/Lib/test/test_urllib2net.py	Wed Mar 20 16:37:26 2013 -0400
@@ -177,6 +177,21 @@
             opener.open(request)
             self.assertEqual(request.get_header('User-agent'),'Test-Agent')
 
+    def test_headers_case_sensitivity(self):
+        url = "http://www.example.com"
+        with support.transient_internet(url):
+            opener = urllib.request.build_opener()
+            request = urllib.request.Request(url)
+            headers = [("Content-Type", "text/plain"), ]
+            opener.addheaders = headers
+            opener.open(request)
+            self.assertTrue(request.has_header('Content-type'))
+            self.assertTrue(request.has_header('Content-Type'))
+            self.assertTrue(request.has_header('content-type'))
+            self.assertEqual(request.get_header('Content-type'), 'text/plain')
+            self.assertEqual(request.get_header('Content-Type'), 'text/plain')
+            self.assertEqual(request.get_header('content-type'), 'text/plain')
+
     def test_sites_no_connection_close(self):
         # Some sites do not send Connection: close header.
         # Verify that those work properly. (#issue12576)
diff -r 66d0f6ef2a7f Lib/urllib/request.py
--- a/Lib/urllib/request.py	Thu Feb 28 18:03:16 2013 +0200
+++ b/Lib/urllib/request.py	Wed Mar 20 16:37:26 2013 -0400
@@ -365,13 +365,13 @@
         self.unredirected_hdrs[key.capitalize()] = val
 
     def has_header(self, header_name):
-        return (header_name in self.headers or
-                header_name in self.unredirected_hdrs)
+        return (header_name.capitalize() in self.headers or
+                header_name.capitalize() in self.unredirected_hdrs)
 
     def get_header(self, header_name, default=None):
         return self.headers.get(
-            header_name,
-            self.unredirected_hdrs.get(header_name, default))
+            header_name.capitalize(),
+            self.unredirected_hdrs.get(header_name.capitalize(), default))
 
     def header_items(self):
         hdrs = self.unredirected_hdrs.copy()