We experienced 9 patients with dorsal nerve impotence whose erection dysfunction showed typically poor sustaining of erection. In order to investigate the characteristics of dorsal nerve impotence, we analized and compared the data of those, on primary diagnostic procedure, vascular as sessment and specialized neurologic evaluation, with other groups. The patients with dorsal nerve impotence showed lower value in penile rigidity than normal subjects on nocturnal penile tumescence that and erotic stimulation test. And PGE1 cavernosometry and cavernosography as vascular assessment showed no significant difference between normal and patients with dorsal nerve impotence in the values of maximal intracavernosal pressure and its falling rate. And sacral evoked potential test as neurologic evaluation showed higher values of sensory, pain, and reflex threshold in patients with dorsal nerve impotence than in normal subjects, without significant difference in bulbocavernosus reflex latency time between two of them. There findings suggest that dorsal nerve impotence can be finally diagnosed by sophisticated neurologic evaluation after psychogenic and vascular etiology of impotence is ruled out.