We report the cryopreservation of epididymal spermatozoa and in vitro fertilization for Japanese monkeys (Macaca fuscata). Ovarian stimulation of seven monkeys was studied by the administration of equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG) during the nonbreeding season, after which oocytes were collected from ovarian follicles. The oocytes were subjected to in vitro fertilization by the frozen-thawed epididymal spermatozoa collected from a male monkey during the nonbreeding season. Before the experiment the epididymides and oocytes were transported about 500 km, during which the epididymides were kept in mineral oil to prevent drying and the oocytes were kept in a maturation medium. This technique of cryopreservation and in vitro fertilization has a wide applicability in nonhuman primate reproduction, including the treatment of infertility and the preservation of wild, nonhuman primates.