diff --git a/Doc/library/csv.rst b/Doc/library/csv.rst
index 9dec7240d9c50fd..263e94a380a2e1f 100644
--- a/Doc/library/csv.rst
+++ b/Doc/library/csv.rst
@@ -275,6 +275,8 @@ The :mod:`csv` module defines the following classes:
       reflecting the parameters found.  If the optional *delimiters* parameter
       is given, it is interpreted as a string containing possible valid
       delimiter characters.
+      If not excluded by the *delimiters* parameter, and if there is ambiguity,
+      then delimiter choice will be biased towards ``[',', '\t', ';', ' ', ':']``.
 
 
    .. method:: has_header(sample)