This study examines the anatomical structure, function and seasonal cyclicity of the male and female reproductive organs of the cave myotis (Myotis velifer) in Texas and southern Arizona. The data indicated that this is a monestrous, seasonally breeding species that stores spermatozoa in both sexes during extended winter torpor or hibernation. The male reproductive cycle was characterized by asynchronous function of the testes (spermatogenesis) and accessory sex organs. Structural factors in both sexes and fructose levels in male accessory organs were evaluated for their significance in prolonged spermatozoa storage. The reproductive anatomy and chronology were similar to other temperate-dwelling vespertilionid bats. Dextral dominance was a feature of the female reproductive tract.