This study was designed to readdress the role of mechanical factors in testicular descent in rodents, with specific attention to the role of the genitofemoral nerve in this process. In a group of newborn rats, the genitofemoral nerve was divided unilaterally and a histologic comparison done of gubernacular and scrotal growth and development and testicular movement between sides. In all animals at birth, the gubernaculum and scrotum were poorly developed bilaterally and the distal gubernaculum was located in the groin and was not attached to the scrotum. The testis was located at or above the inguinal ring. With post-natal maturation, the processus vaginalis and gubernaculum advanced beyond the groin into the scrotum, and the scrotum developed to accomodate the testis on the control or normal side only. The testis started to descend into the scrotum only after these anatomic events occurred. Sectioning of the genitofemoral nerve aborted this process. This study suggests that inguinoscrotal testicular descent is an active process requiring gubernacular migration that is dependent on the genitofemoral nerve.