Objective: To reveal if the use of antimicrobi als is rational in the authors hospital.　Methods: 1 025 cases were investigated retrospectively by systematic sampling from all the inp atients of the year 1997.　Results: 77.8% of the subjects were treated with antimicrobials, of whom, 55.2% treated with 2 or more antimicr obials. Yet only 39 cases had microbiological test before the administration of antimicrobials.　Conclusion: Inappropriate use of antimicr obials exists in the hospital. The management of the use of antimicrobials and c ontinuing education of medical doctors should be enhanced so as to make the use of antimicrobials more rational.