Bryan already posted a study on this. It was done back in the 1960's. A researcher tracked down 26 castrated men and asked to see photographs of them before and after they were castrated, and interview them and inspected them. He did not do hair counts. He found out the age the were castrated. Every castrated man did not lose any more hair, even the 15 year old did not lose his very low hair line after 20 years. Appearantly, they did not regrow any hair either, if they had male pattern baldness before castration. Many here suspect they did, but just not enough to be obvious in random photographs, or enough for the men themselves to notice it in the mirror. One of them did obviously have a little more hair in the vertex. As stated earlier, no before and after hair counts were done.