We reported a case of a 24-year-old man who had frequent sleep attacks beginning 4 years after a head trauma. He showed frequent episodes of excessive daytime sleepiness and cataplexy which were triggered by emotional excitement. He also complained of sleep paralysis and hypnagogic hallucination. An overnight polysomnography revealed the sleep onset REM stage as typically observed in narcoleptic patients. The HLA typing was negative for DR2 and DQw1. He was diagnosed as having HLA-DR2 and DQw1 negative-post-traumatic narcolepsy. Peroral pemoline suppressed excessive daytime sleepiness, sleep paralysis and hypnagogic hallucination with dramatic relief of cataplectic attacks by the addition of imipramine. It has been reported that more than 90% of narcoleptic patients are HLA-DR2 and-DQw1 positive. About 10% of the narcolepsy patients were regarded as symptomatic due to brain tumors, cerebrovascular disorders, head trauma, multiple sclerosis, encephalitis and so on, which mainly affect the brainstem or diencephalon. Thus far, narcolepsy is considered to develop depending on both the genetic background including HLA types, and exogenous factors. According to reported cases with narcolepsy, sporadic cases were HLA-DR2 positive even more frequently than familial cases. To date, however, there have been only three previous reports of a symptomatic narcolepsy patient without association of HLA-DR2 and DQw1. In conclusion, the present report suggests that typical symptomatic narcolepsy could be HLA-DR2 or DQw1 negative.