Industrialization has introduced various working systems into the modern society. Shiftwork is a good representative among those. So far various adverse health effects, possibly caused by this shiftwork, have mainly been reported in the fields of manufacturing industry by many other researchers , sleep disorders, gastrointestinal disorders and cardiovascular disorders and so on. These health effects were thought to be caused by the changes of circadian rhythm on shiftworking. This study was especially planned to evaluate effects of shiftwork on sleep disorders among shift-working medical manpower like hospital nurses, important persons dealings with lives, and ultimately to provide them with basic evidence for improving work environment. The study subjects were arbitrarily selected among shift-working female nurses and day-working female pharmacists in one university hospital in Seoul, and finally 79 nurses and 58 pharmacists were enrolled. The research was conducted by using self administered questionnaire, consisting of items about socio-behavioral factors including demographic factors which can affect sleep patterns and questions which make it possible to evaluate sleep disorders (e. g. sleeping duration, sleep latency, re-sleep latency, days of insomnia per week, drug use for sleep, and subjective symptoms). The result showed that the shiftworkers had significantly longer sleep and re-sleep latency, more days of insomnia, and a stronger likelihood of using drugs when they had sleep difficulty than day-working pharmacists. And the number of nightshift duties per month was discovered as the only significant predictor of sleep latency. Additionally, the subjective symptoms related to sleep disorders when awake and at work, showed negligible differences between the shiftworkers and dayworkers. In conclusion, we found shiftwork was risk factor for sleep disorders.