it is an antiandrogen, i.e. it suppresses the actions of testosterone (and its metabolite dihydrotestosterone) on tissues. It acts by blocking androgen receptors which prevents androgens from binding to them and suppresses luteinizing hormone (which in turn reduces testosterone levels). Its main indications are prostate cancer, benign prostatic hyperplasia, priapism, hypersexuality and other conditions in which androgen action maintains the disease process. Due to its anti-androgen effect, it can also be used to treat hirsutism, hope this helps