The cause of premature ejaculation (PE) has been thought to be psychological in the majority of patients but we investigated penile hypersensitivity for an organic basis of PE. For another organic basis of PE, we have suggested hyperexcitability of the ejaculation center. SS-cream is a topical agent containing 9 oriental herbs for treating PE. Clinically SS-cream has been effective in the treatment of PE. Therefore, in order to implicate the organic basis of PE and realize the effect of SS-cream on PE, we investigated the somatosensory evoked potential (SEP) in patients with PE(16 cases) and the effects of SS-cream on SEP for treating PE. The latencies and amplitudes of the evoked responses were measured by two different places in stimuli, one was on the penile shaft with ring electrode and the other on the glans penis with a surface electrode. The latency of SEP stimulated at the glans penis was significantly longer than that stimulated at the penile shaft (p< 0.05). The latency stimulated at the glans penis after applying SS-cream was significantly longer than before applying SS-cream (p< 0.05), which was near the level of a normal potent man. But the latency stimulated at the penile shaft has no significant difference between before and after the application of SS-cream (P > 0.05). The amplitudes of the evoked responses stimulated at the glans penis were significantly higher than those stimulated at penile shaft (p< 0.05). And both these amplitudes were significantly reduced with the application of SS-cream (p< 0.05). With these result, we can suggest that the patients with PE have glans penile hyperexcitability and it provides further implications for an organic basis of PE, SEP stimulated at the glans penis can be a very useful method to evaluate PE, along with SEP stimulated a penile shaft and SS-cream prolongs the sensory conduction and reduces the penile hyperexcitability of the patient with PE.