The distributions of the VIPergic and catecholaminergic nerves as a part of autonomic nerve system in the human male reproductive organs were studied with immunohistochemical technique. In the corpus cavernosum and corpus spongiosum, a large number of VIPergic and catecholaminergic nerve fibers were observed especially along the blood vessels. In the seminal vesicle and prostate, the VIPergic nerve fibers were equally distributed in both mucosal and muscular layers, while the catecholaminergic nerve fibers were mainly distributed in the smooth muscle layer. In the vas deferens, the VIPergic verve fivers were closely related to the basement membrane of epithelium. These results suggest that the VIPergic nerves play important roles in vascular reaction and epithelial activities, while the catecholaminergic nerves were involved in smooth muscle actions.