['To assess the impact of a continuous quality-improvement program on nosocomial infection rates.', 'Prospective single-center study in the medical-surgical ICU of a tertiary care center. PATIENTS. We admitted 1764 patients during the 5-year study period (1995-2000); 55% were mechanically ventilated and 21% died. Mean SAPS II was 37+/-21 points and mean length of ICU stay was 9.7+/-16.1 days.', 'Implementation of an infection control program based on international recommendations. The program was updated regularly according to infection and colonization rates and reports in the literature.', 'Prospective surveillance showed the following rates per 1000 procedure days: ventilator-associated pneumonia (VAP) 8.7, urinary tract infection (UTI) 17.2, central venous catheter (CVC) colonization 6.1, and CVC-related bacteremia and 2.0; arterial catheter colonization did not occur. In the 5 years following implementation of the infection control program there was a significant decline in the rate per patient days of UTI, CVC colonization, and CVC-related bacteremia but not VAP. Between the first and second 2.5-year periods the time to infection increased significantly for UTI and CVC-related colonization.'] Does a continuous quality-improvement program reduce nosocomial infection rates in the ICU?