In patients with polycystic ovarian disease (PCOD) ovulation was induced with a combination of human menopausal gonadotropin (hMG) and human chorionic gonadotropin (hCG) or with urinary follicle-stimulating hormone (uFSH; Metrodin, Serono Laboratories, Inc., Randolph, MA) alone. hMG/hCG and uFSH resulted in comparable rates of ovulation and conception in patients with PCOD. The incidence of hyperstimulation and the potential for multiple births appeared lower with uFSH. The fact that endogenous ovulation did not occur in hMG patients who had hCG withheld or in 3 of the 11 uFSH patients who had preovulatory levels of estradiol and follicles greater than 15 mm may imply that these similarly derived gonadotropins in some instances block endogenous ovulation.