Purpose: The purpose of this study is to determine the risk adjusted nosocomial infection (NI) rate and distribution of Nls and their causative pathogens in adult lCU. Methods: Prospective surveillance was performed at 12 lCU's of 5 acute care hospitals in Seoul and Kyonggi Do during a 3-months period from May to July 2002. The case finding was done by direct reviews of medical charts regularly for all patients by ICPs using CDC definitions. Results: Total NI rate was 10.18/1,000 patient-days in Medical-surgical ICU (MSICU) and 12.35/1,000 patient-days in Neurosurgucal ICU(NCI). Risk adjusted infection rate was 3.44 in indwelling catheter associated UTI 2.12 in central line associated BSI. 3.51/1,000 device-days in ventilator associated pneumonia in MSICU. There were 3.72, 2.26, 6.06/1,000 device-days in NCU. The infection rate by leu type showed no significant difference. The distribution of Nls were PNEU (28.99%). UTI (28.99%), BSI (18,84%), SSI(4.35%) in MSICU, and UTI(48.0%), PNEU(24.0%), BSI (14.0%), SSI(6.I) in NCU. The most commonly isolated organisms were Candida spp (38.6%), Enterococcus spp. (13.4%) in UTI, Staphylococcus aureus(36.2%), p. aeruginosa(18.8%) in PNEU and Coagulase negative staphylococcus(44.1%). S. aureus (14.7%) in BSL, S. aureus (19.8%) was the most common organism from overall nosocomial infections in the ICU, and 96.3% of S. aureus were MRSA. Conclusion: Distribution of site-specific nosocomial infection and isolated organisms were similar to the results of KOSNIC (Korea society for nosocomial infection control) surveillance in 1996. However, the total infection rate and a risk adjusted infection rate at MSJCU is lower than 1996's. This decrease is considered to be a result of efforts to prevention and control nosocomial infections.