This is a bit of a guess, but without some sample data and code, that's the most you can hope for: When you dynamically add elements to a page with Javascript, they may not automatically be recognized by your browser as part of the form in question. I know that, in jQuery, elements added after the initial page load are not bound to events by default. For instance, a click function that you bind to all buttons will not be bound to new buttons that are added later, unless you redo the binding or use some other special method like delegation. I don't know if the same sort of thing happens with plain Javascript and form fields, but it could be a place to look. If you're certain that the dynamic fields are not appearing in the POST data, then the Perl script on the server that processes the data isn't your problem; you'll have to look at how the fields are being added.