I've actually been wondering about this for some time, but now I have a reason to ask. One of my friends is applied to a sperm bank to be a sperm donor and was accepted and on his first interview he will have to give a large sample of sperm. He has to abstain from ejaculating for 2-3 days, but he's not sure whether abstaining from pot is a good idea or not as well. Now I know quite a bit about the marijuana myths and obviously so many of the propaganda lies have been de-bunked and disproven. For example it is a scientific fact that cannabis does not lower testosterone count. Ganja does not lower immune function. Nor is there a an established link between lung cancer and weed smoking. However the question of sperm count is still up for question. There were studies done in the 1970s by researchers that supposedly showed smoking pot can reduce sperm count and seminal fluid. But these results were hard to replicate....though some studies later on with insanely high amounts of THC (like 20 joints a day for a month) can lower sperm count in animal studies (of course even very heavy users smoke a lot less than this I think). Since then not a lot has been done to disprove it, but a lot of these studies have been outdated. However I have seen more recent articles (2003ish at least, by the bbc) that reported lower sperm count, less seminal fluid, and sperm swimming too fast increasing infertility. Now have there been any studies (recent or otherwise) that have disproved these claims of lowered sperm count? Should my friend stop smoking pot during this evaluation and maybe even during donation from now on, or is there nothing to worry about here? The weird thing is that I personally never feel a loss in sexual function and if anything I get more horny and seemingly more seminal fluid (or at least as much) in my ejaculations, so it seems like any sort of damage here wouldn't occur with my friend, who reports a similar reaction.