I've donated, but it was only a small amount (just a test sample, from the hip). Just a little pain during the actual donation, the worst part was the sound of bone going "crunch." they just used a thick heavy needle to poke through where it was thin. Had a bruise there that lasted a few days, no big deal. A female coworker donated after I did, she complained a lot about the bruising part. Not sure how much it really hurt her or if she wanted an excuse to b!tch at me since I told her it wasn't that bad.