Based on techniques developed for the domestic cat, in vitro fertilization (IVF) studies were conducted in the taxonomically related leopard cat (Felis bengalensis). Adult females received pregnant mares' serum gonadotropin (PMSG) followed 80 or 84 h later by human chorionic gonadotropin (hCG) on two to four occasions over a 40-day to 27-month interval. Oocytes were collected laparoscopically from ovarian follicles 25-27 h after hCG and co-cultured with processed, homologous spermatozoa (37 degrees C, 5% CO2 in air, humidified atmosphere) for 30-36 h. There was no apparent ovarian refractoriness to repeated treatments with exogenous gonadotropins. Overall, the mean number of mature follicles present and the total number of oocytes and proportion of immature oocytes collected did not differ (P greater than 0.05) between the 80 h (4.9 +/- 0.9; 4.7 +/- 1.2; 14.9%, respectively) and 84 h (5.6 +/- 1.4; 5.4 +/- 1.7; 22.2%, respectively) gonadotropin interval groups. However, the proportion of mature leopard cat oocytes fertilized in vitro, as determined by embryonic cleavage, was increased (P less than 0.005) by extending the interval between PMSG and hCG from 80 (17.5%) to 84 (52.4%) h. These data 1) demonstrate that, compared to the domestic cat, the ovaries of the leopard cat are less responsive to a given PMSG/hCG treatment; 2) indicate that leopard cat follicular oocytes can be recovered readily by laparoscopy and are capable of becoming fertilized in vitro; and 3) suggest that IVF may be a viable approach for producing embryos and perhaps enhancing captive propagation of rare Felidae.