Hidden field in search form

Please help..

I'm trying to add a hidden field to the adv search form.
What is the best way to achieve this?

Thank you any ideas.

Why do you want it if it's hidden?  You could just create the function and not echo it, that will keep it hidden for you.

Thanks for your reply.

I want the field hidden but still passed in the in URL (i.e. ?ProfileType=1) so that the results will be filtered accordingly - unless there is a better way to do this. By default it's a select field which is what I want for the join form but in the search form I only want one specific profile type to show up in the search results.