Background: The brain seems to be inherently feminine. Masculine characteristics of the structure and functions are imposed on developing CNS by the action of testicular hormones during a critical embryonic period. Testosterone is a prohoromone responsible for sexually dimorphic characteristics of the brain. A number of structural sex differences in the human brain have been reported, but their functional significance are less well established. Brain function in men appears to be more lateralized than women and this may be the reason that women are more likely than men to recover speech, after a stroke that damages cortical speech areas. Objective: this study examines the effects of testosterone on sexually dimorphic nucleus of the rat spinal cord i.e. the spinal nucleus of the bulbocavernosus muscle, which innervates two sexually dimorphic, androgen-sensitive perineal muscles that are active during copulation, the bulbocavernosus and levator ani. Methods: the study was performed on litters of albino rats. Their pregnant mothers received on embryonic days (E16-E20) subcutaneous injection of 2mg of testosterone propionate. The spinal nucleus of bulbocavernosus was examined in control group, female litters with and without prenatal testosterone injection. Results: It was demonstrated that perinatal injection of testosterone prevented the involution of spinal nucleus of bulbocavernosus in the female rats. Conclusions: It is concluded that androgens have a sparing effect on the motor neurons of this nucleus that prevent the developmental cell death of neuronal cells. The mechanism of the effects of androgen are discussed, whether it is through direct effect of androgen on motor neurons themselves, or indirect effect as a result of the androgen action on the target androgen-sensitive perineal muscles.