To identify the factors related to the readmission and ambulatory visit we analyzed the data in discharge abstract DB(DADB) and outpatient database(OPDB) for 19,983 patients discharged in 1990 from an university hospital(S Hospital) in Seoul. The target patients were limited to those who didn' t have previous episode of discharge in that hospital. Readmission data for 10 years(1990-1999) and ambulatory visit data for 5 years(1995-1999) were analyzed by using x2 test and multiple logistic regression analysis. The main results of this study is as follows. 1) As the number of readmission was increased, readmission rate(RR) was also increased while the average length of stay(ALOS) was decreased. 2) RR was higher in male, transferred from other health care facilities, with consultation, biopsy, ICU care episode during hospitalization. 3) In logistic regression, RR of patients living close to S Hospital hospital was higher than the others wh?n other variables were adjusted. 4) RR of the patients with the diagnosis(Dx) of cancer or cancer related condition was the highest(47.6%), and the consistency rate (CR) of principal Dx group with that of previous admission was also the highest in cancer patients. As the number of readmission was increased the CR of Dx group was also increased. 5) 23.4%(4866) of the target patients had episode of visiting outpatient dispensary(OPD) for between 1995-1999 and the average number of visit was 13.6 times. Patients with the Dx of heart disease showed the highest proportion in ambulatory visit.