Patients with Parkinson's disease have been known to have sleep disturbances of various types. Zolpidem tartrate, an imidazopyrimidine short-acting hypnotic drug used treat insominia and several patients with PD have described a significant improvement of parkinsonian symptoms after administration of zolpidem tartrate. We tried to evaluate effect of zolpidem tartrate for sleep disturbances in patients with PD by a Japanese version of Chaudhuri's Parkinson's disease Sleep Scale (PDSS) and Unified Parkinson's disease rating Scale (UPDRS) motor scale. Twelve patients with PD (mean age 67.4 years old, range 40-77 years old) were evaluated by PDSS and UPDRS before and two weeks after prescribed zolpidem tartrate 5 mg per day. Patients showed improvement in items relating overall sleep disturbances, sleep refreshment and morning stiffness. Disabilities remained unchanged before and two weeks after prescribing zolipdem tartrate. Zolpidem tartrate may be useful for sleep disturbances in patients with PD and for improving their quality of daily livings.