diff --git a/github2/pull_requests.py b/github2/pull_requests.py
index fe8ef1b..09f92e5 100644
--- a/github2/pull_requests.py
+++ b/github2/pull_requests.py
@@ -53,7 +53,7 @@ def create(self, project, base, head, title=None, body=None, issue=None):
         issue.  If an ``issue`` parameter is supplied the pull request is
         attached to that issue, else a new pull request is created.
 
-        :param str project: Github project
+        :param str project: the Github project to send the pull request to
         :param str base: branch changes should be pulled into
         :param str head: branch of the changes to be pulled
         :param str title: title for pull request
@@ -67,6 +67,10 @@ def create(self, project, base, head, title=None, body=None, issue=None):
             post_data["title"] = title
             if body:
                 post_data["body"] = body
+        else:
+            raise TypeError("You must either specify a title for the "
+                            "pull request or an issue number to which the "
+                            "pull request should be attached.")
         pull_request_data = [("pull[%s]" % k, v) for k, v in post_data.items()]
         return self.get_value(project, post_data=dict(pull_request_data),
             filter="pull", datatype=PullRequest)