proviron is a mild anti-e, that works more like arimidex then nolva, in the sense that it stops aromatizing from happening, (nolva blocks estrogen at certain sights,,nipples)....but it is very mild in action, so a lot of guys wont use it for that purpose...now it does have the ability to free up more test, so in that sense its worth using...also it has the ability to give your muscles a harder look , which is why some use it during their contest prep. ive also heard it helps with your sex drive, but ive never noticed anything like that....so bottom line is, its worth using, but i wouldnt depend on it for its anti-e capabilties......LP