Background: Nosocomial infection control is one of important means to assure the quality of medical care in the hospital, however, it has been neglected by most of the hospital personnels. Of nosocomial infections, urinary tract infection is the highest incidence, which is related to the indwelling catheter. It is, therefore, necessary to pay primary attention to the patients with the indwelling catheter in intensive care unit in order to control nosocomial Infection and to improve the quality of medical care in the hospital. Methods : The subjects of this study were patients with indwelling catheter who were admitted to the ICU of Pusan Paik Hospital from March 1994 to May 1995. The author calculated UTI rate among the subjects through the cultivation of the urine, identified the related factors of the UTI through brain storming of study team and head nurses working at ICU, and analized the effectiveness of the proposed approaches through comparing the infection rates of before and after activities. Results : The major activities carried out by the study team were to conduct in-service education programs for the staffs working at ICU about the importance of the nosocomial infection control in QA, and nursing intervention to reduce the UTI rate among the patients with indwelling catether. 1. The major nursing interventions that the study team had implemented were as follows ; 1) Drainage system was changed from partial open system to completely closed system. 2) Bladder irrigation which was routinely practised in all patients stopped among the noninfected patients. 3) Bladder irrigation set was changed to the disposable one. 4) Catheter was inserted under the anesthesia for patients to be operated. 5) Male patient receiving wrapped with gauze after perineal care was not wrapped. 6) Clamp which had not been before was newly attached to drainage tube. 7) Urine bag which had been packed into a lot of pieces was done into each piece. 8) The interval of change of indwelling catheter had regularly been four weeks, however it was used continously until it worked well. 9) Catheter was attached well at the defined site. 10) Paper towel was used instead of cotton towel. 11) Mats at the entrance were removed and cleansing of wards was enhanced. 2. The UTI rate by month was 34.4% in maximum and 9.8% in minimum during the period of this study, however it had gradually decreased. After 6 months from initiating infection control activities, the trend of rates was relatively stable. It was identified that UTI rate was different by season 12.5% in winter and 27.2% in summer. 3. Utilization rate of indwelling catheter was maintained at under 50%, but it was increased above 57% from April 1995. 4. The number of bladder irrigation sets used per day was 33.3 sets in maximum and 2.8 sets in minimum. The number used per day were also remarkably deceased. Conclusion : It was found that a program to control UTI could contribute to nosocomial infection control, and it was, in turn, a mean to assure the quality of medical care in the hospital. The nursing interventions which this study team had implemented were effective in the reduce of UTI rates.