31 female cynomologous macaques (Macaca fascicularis), were investigated by laparoscopy to evaluate ovarian morphology and follicular development near ovulation. Serial observations were begun 15 days prior to the end of the menstrual cycle. Generalized swelling and darkening of the ovary characterized the developing follicle 24 h prior to ovulation; a specific pattern of blood vessels associated with the follicle developed 8 h prior to ovulation; and corpora hemorrhagica were morphologically identifiable 12-24 h following ovulation. Future prediction of ovulation time may be accomplished by a single laparoscopic examination.