Some patients undergoing in vitro fertilization have had a previous oophorectomy. The purpose of this study was to provide a preliminary comparison of the follicular response to ovulation induction with sequential clomiphene citrate and human menopausal gonadotropin (hMG) in patients with one (n = 14) or two (n = 14) ovaries. No statistically significant differences were detectable in the following parameters: mean number of ampules of hMG required, mean number of days of hMG therapy, mean number of follicles greater than 15 mm on ultrasound, mean number of mature or number of immature oocytes, mean number of embryos transferred, and number of pregnancies. Patients with both ovaries in situ demonstrated a trend for greater numbers of follicles greater than 15 mm aspirated at laparoscopy (5.9 versus 3.4, P = 0.03). We conclude that the presence of a single ovary does not appear to influence the outcome of in vitro fertilization.