Among 1099 patients seen over an 8 yr period for amenorrhea or oligomenorrhea, 115 (10.5%) had developed amenorrhea after ceasing oral contraception. These patients were the subject of a special study. Those who were treated received either clomiphene alone, hMG/hCG [human menopausal gonadotropin/human chorionic gonadotropin] therapy, or both. There was no correlation between the incidence of either spontaneous or treatment-induced ovulation and menstruation and the duration of use of oral contraception, previous parity, or the nature of prior menstrual cycles. The incidence of treatment-induced resumption of menses was essentially the same as that for spontaneous resumption. An average duration of 30 mo. of oral contraceptive use did not significantly affect urinary excretion levels of estrogens and gonadotropins. The postpill amenorrhea syndrome is apparently caused by oversuppression of hypothalamic-pituitary function.