diff --git a/bigquery/google/cloud/bigquery/query.py b/bigquery/google/cloud/bigquery/query.py
index 3c2e398e5f41..6b764f3c664d 100644
--- a/bigquery/google/cloud/bigquery/query.py
+++ b/bigquery/google/cloud/bigquery/query.py
@@ -383,7 +383,14 @@ def fetch_data(self, max_results=None, page_token=None, start_index=None,
 
         :type timeout_ms: int
         :param timeout_ms:
-            (Optional) timeout, in milliseconds, to wait for query to complete
+            (Optional) How long to wait for the query to complete, in
+            milliseconds, before the request times out and returns. Note that
+            this is only a timeout for the request, not the query. If the query
+            takes longer to run than the timeout value, the call returns
+            without any results and with the 'jobComplete' flag set to false.
+            You can call GetQueryResults() to wait for the query to complete
+            and read the results. The default value is 10000 milliseconds (10
+            seconds).
 
         :type client: :class:`~google.cloud.bigquery.client.Client` or
                       ``NoneType``