One hundred forty-four women suffering from obstructive tubal disease underwent laparoscopy for in vitro fertilization and embryo transfer (IVF-ET). Ovulation was induced by a human menopausal gonadotropin/human chorionic gonadotropin (hMG/hCG) protocol. The patients were divided according to their estradiol (E2) response to hMG/hCG administration: group A, an increase of E2 levels on the day after hCG administration (day +1); group B, a decrease of E2 levels on the day after hCG administration. Each of these groups was further subdivided into high responders (E2 greater than 500 pg/ml on day 0), designated A-1 and B-1, respectively, and low responders (E2 less than 500 pg/ml on day 0), designated A-2 and B-2, respectively. Patients responding in an A-1 pattern had significantly higher E2 levels from day 0 to day +8. Fertilization and cleavage rates did not differ among the groups, nor did luteal-phase progesterone. Twenty-one pregnancies were achieved from 126 transfers (17%), of which 16 (75%) occurred in women responding in an A pattern. We recommend that laparoscopy be deferred in women responding with a B pattern, because this preselection may increase pregnancy rates per IVF-ET cycle.