Index: wp-includes/template-functions-post.php
===================================================================
--- wp-includes/template-functions-post.php	(revision 3548)
+++ wp-includes/template-functions-post.php	(working copy)
@@ -258,9 +258,12 @@
 	if ( $keys = get_post_custom_keys() ) {
 		echo "<ul class='post-meta'>\n";
 		foreach ( $keys as $key ) {
-			$values = array_map('trim', get_post_custom_values($key));
-			$value = implode($values,', ');
-			echo "<li><span class='post-meta-key'>$key:</span> $value</li>\n";
+			$keyt = trim($key);
+			if ($keyt{0} != '_') {
+				$values = array_map('trim', get_post_custom_values($key));
+				$value = implode($values,', ');
+				echo "<li><span class='post-meta-key'>$key:</span> $value</li>\n";
+			}
 		}
 		echo "</ul>\n";
 	}