Two hundred fifty women with hirsutism were studied, with a mean age of 25.5 years (ranging from 13 to 38 years). The evolution of hirsutism varied from 3 months to 13 years, being minimal in 82 patients (33%), mild to 101 (40%), moderate in 56 (23%) and severe in the remaining 11 women (4%). Polycystic ovary syndrome (PCOS) was diagnosed in 134 patients (53%), overweight or obesity in 45 (18%), late-onset adrenal hyperplasia in five (2%), ovarian tumor in two (0.8%), drug-induced hirsutism and Cushing's syndrome in one patient each (0.4%), and idiopathic hirsutism in 62 cases (25%). Among 67 patients with moderate or severe hirsutism, testosterone was elevated in 21 (31%). In 117 out of 206 (57%) cases polycystic ovaries were observed by ultrasound. Fifty-four patients were treated with a combination of 2 mg cyproterone acetate and 0.035 mg ethinyl estradiol, observing improvement of hirsutism in 32 patients (59%). It is concluded that PCOS is the most frequent cause of hirsutism, but an important proportion of cases without evident etiology remain classified as idiopathic hirsutism.