Don't forget that QUERY_STRING will be URL encoded. (spaces become +, non-word characters become %(hex values)) , which is why CGI.pm is generally used to decode the various possibilities. Nonetheless, sometimes you want a "clean" URL, such as www.mypage.com/detail.cgi?5 , so you can use QUERY_STRING to check that. Note also that you can use QUERY_STRING while using CGI.pm to handle other aspects of CGI programming.