I had a lumbar puncture, aka spinal tap. it really was no big deal. no pain while it was being done. Dahlek covered it well, i would just add, dont let them rushyou out of wherever you are getting it done. you should lay down afterwards at the place you are getting it done for at least 45 minutes. dont let them rush you out! if you can use a car where you can either lay flat in the backon the way home or where the seat goes back pretty far. the longer you can lay flat and the more you do in the few days after the less of a chance of you getting the headache. dont be afraid of the procedure, plus it can get you answers that you need either by finding something or not finding something. mine was totally negative.