A better understanding of the polycystic ovary syndrome (POS) may help to institute a more rational treatment adapted to each individual case. Seven therapeutic methods have been used until now, progestogens constituting the minimal treatment. Combined oestrogen and progestogen therapy remains basic as long as pregnancy is not desired and should include an anti-androgenic progestogen if hirsutism is to be reduced. Anti-oestrogens have dramatically improved the treatment of sterility and could be used against POS with certain precautions. Parenteral gonadotropins of the HMG variety are usually contra-indicated. Ovarian wedge resection has few indications in view of the risk of post-operative adhesions. Dexamethasone has restored ovulation in some cases. Bromocriptine has recently given promising results. The indications of these various treatments depend on the results to be achieved: endometrial carcinoma must always be prevented, regular menstrual cycles should often be re-established, hirsutism must be avoided or reduced, and fertility should be restored or at least preserved for the future by breaking the hormonal vicious circle. The high incidence of obesity and a possible desire for contraception should also be taken into account.