diff --git a/hgext/convert/convcmd.py b/hgext/convert/convcmd.py
--- a/hgext/convert/convcmd.py
+++ b/hgext/convert/convcmd.py
@@ -198,7 +198,8 @@ class converter(object):
         afile = open(authorfile, 'r')
         for line in afile:
 
-            if line.strip() == '':
+            line = line.strip()
+            if not line or line.startswith('#'):
                 continue
 
             try:
diff --git a/tests/test-convert-authormap b/tests/test-convert-authormap
--- a/tests/test-convert-authormap
+++ b/tests/test-convert-authormap
@@ -16,6 +16,7 @@ cd ..
 cat > authormap.txt <<EOF
 user name = Long User Name
 
+# comment
 this line is ignored
 EOF