The Department of Dentistry and Oral Surgery at Yukoukai Hospital was established in April 1980. As of December 31, 1985, the total number of inpatients treated was 587 and that of outpatients 17, 975. These numbers increased year by year. We report here some clinical and statistical observations on our inpatients. The incidence of diseases was as follows: trauma: 50.0%, inflammatory diseases: 33.0%, cysts: 11.8%, tumors: 1. 1%, diseases of salivary glands: 0.6%, diseases of temporomandibular joint: 0.5%, and others: 2.9%. As can be seen, trauma and inflammatory diseases accounted for a vast majority of the diseases of inpatients. Emergency hospitalization was necessary for, 74.8% of the inpatients, 41.0% of whom were hospitalized outside regular hours (i.e., at night or on holidays).