The present studies were conducted to investigate the possibility of capacitation of bull spermatozoa in the uteri isolated from estrous hamsters and to investigate the possibility of in vitro fertilization of follicular oocytes matured in culture, using ejaculat spermatozoa preincubated in the uteri isolated from estrous hamsters. The follicuar oocytes matured in culture were not fertilized after insemination spermatozoa preincubated for 3 and 5.5-7 h in the uteri isolated from estrou hamsters, but 5, 77, 85 and 50-67% of those oocytes were fertilized by spermatozoa preincubated for 3.5, 4, 4.5 and 5h in those uteri, respectively.