PURPOSE: To evaiuate the reliability of penile biothesiometry, vibration-induced ejaculation (VIE) test for evaluation of the penile hypersensitivity, and the reliability of bulbocavernous reflex latency (BCRL) test and dorsal nerve somatosensory evoked potential (DNSEP) test for evaluation of the nerve conduction pathway of penis. MATERIALS AND METHODS: Penile biothesiometry, VIE test, BCRL test and DNSEP test were done in 20 normal men (mean age: 38.9 years) and 30 patients with premature ejaculation (mean age: 40.1 years) without history of prostatitis, neurological disorders nor medication of drugs influence nerve system. RESULTS: There were no significant differences in vibration perception threshold of penis, VIE test and DNSEP test between the two groups. However, BCRL decreased significantly in patients with premature ejacualtion (34.1+/-4.95 msec) than in the control (37.0+/-4.71 msec). CONCLUSIONS: Our results suggest that earlier excitation of the sacral reflex are might be related with the premature ejaculation.