The proximal and distal attachments of the gubernaculum were severed in neonatal rats to examine their role in testicular descent and their relationship to transection of the genitofemoral nerve, which prevents descent of the testis. In 34 of 82 animals proximal transection of the gubernaculum resulted in descent of the testis. In 18 animals the testis remained in the abdomen but in both groups the processus vaginalis developed, suggesting that failure of descent was accidental and not caused by scrotal maldevelopment. Distal transection resulted in failure of descent and prevented growth of the processus vaginalis in all 27 rats. These results suggest that distal transection of the gubernaculum is equivalent to division of the genitofemoral nerve, which supplies the gubernaculum through its distal attachment. Because denervation of the gubernaculum prevents the effect of androgens on gubernacular differentiation, the results suggest that testosterone acts via the nerve. The putative effect of androgens on the gubernaculum may be mediated indirectly by the central nervous system, rather than directly on the gubernaculum itself.