An extended regimen of clomiphene consisting of 250 mg of clomiphene for 8 days followed by the administration of 10,000 IU of human chorionic gonadotropin (hCG) 6 days later was administered to 13 oligomenorrheic women who had previously failed to ovulate when treated with 250 mg of clomiphene for 5 days and hCG. Eight of these 13 women ovulated. Their postovulatory mean progesterone (P) level 7 days after hCG was 16 +/- 2 ng/ml. Three pregnancies occurred during 25 treatment cycles. Posttreatment estrogen levels were higher when women were treated for 8 days than for 5 days. Women ovulating after 8 days of treatment had increased concentrations of luteinizing hormone (LH) and testosterone (T) prior to hCG administration and higher pretreatment levels of estrogen and T, compared with women who did not ovulate. Changes in the timing of hCG administration may induce ovulation in some women who fail to ovulate when hCG is given on day 14. Because this 8-day regimen of clomiphene and hCG was successful in more than 50% of women failing to ovulate after 5 days, this regimen should be used prior to human menopausal gonadotropin (hMG) therapy.