Ovulation induction in polycystic ovary syndrome (PCOS) with human menopausal gonadotropins (hMG) results in suboptimal cycle fecundity and frequently is complicated by ovarian hyperstimulation. The use of a gonadotropin releasing-hormone agonist (Gn-RH-a) with hMG induction of ovulation may improve the therapeutic outcome. In this prospective, randomized trial, 27 women with PCOS underwent a total of 25 cycles of hMG alone and 33 cycles with adjunctive GnRH-a (leuprolide) treatment. Premature luteinization was seen less frequently in the leuprolide-treated cycles than in cycles treated with hMG alone. There were no differences between the treatments in ovarian sensitivity to hMG. Cycle fecundity was 0.16 for hMG alone cycles, and 0.27 for leuprolide with hMG cycles, which were not statistically different. We conclude that the sensitivity of the PCOS ovary to hMG is not affected by 4 weeks of leuprolide pretreatment.