Serum hormonal profiles were characterized in 126 treatment cycles from 24 anovulatory women who underwent ovulation induction therapy with sequential human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG). Of the 98 presumptively ovulatory treatment cycles, 18 had luteal phases lasting 11 days or less. Sixteen of these 18 cycles had one or more of the following features: serum hCG concentrations of less than 75 mIU/ml 24 hours after hCG administration or peak preovulatory estradiol (E2) levels either less than 200 pg/ml or greater than 2000 pg/ml. Midluteal serum progesterone levels were less than 10 ng/ml in seven of the shortened cycles. Only one of these features (E2 greater than 2000 pg/ml) was present in any cycle (n = 2) resulting in pregnancy. Our observations suggest that serum E2 and hCG levels will reflect the apparent adequacy of luteal function during hMG/hCG treatment cycles.