We studied risk factors for nosocomial infections among 500 critically ill children who were admitted to a pediatric intensive care unit from August 1994 through August 1996 and who were prospectively followed until death, transfer, or discharge. Age, gender, postoperative state, length of stay, device-utilization ratio, pediatric risk of mortality score, and total parenteral nutrition were the risk factors studied. Through multivariate analysis, we identified three independent risk factors for nosocomial infection: device-utilization ratio (odds ratio [OR], 1.6; 95% confidence interval [CI95], 1.10-2.34), total parenteral nutrition (OR, 2.5; CI95, 1.05 5.81) and length of stay (OR, 1.7; CI95, 1.31-2.21).