OBJECTIVE To explore the incidence of the nosocomial infection in patients with mental diseases,analyze the correlative factors and then reduce the incidence.METHODS By using the retrospective method,the inpatient cases in Department of Psychotherapy from Jan 2000 to Dec 2005 were surveyed and statistically analyzed.RESULTS There were 307 cases of nosocomial infection from 4175 inpatients with mental diseases.The infection rate was 7.35%.The total rate had been dropped year by year.The major sites of the infection were the upper respiratory tract,the gastrointestinal tract and the lower respiratory tract.CONCLUSIONS The incidence of the nosocomial infection is related with fallowing factors:the characteristic of patients,the crowded wards,the changing seasons and the side-effect of drug.