Background and aims: It is not well-known whether age or the severity of underlying conditions affects mortality in critically ill patients. The aim of this study was therefore to determine whether age is an independent predictor of hospital survival for critically ill patients. Methods: Patients consecutively admitted to the intensive care unit from December 1 1999 to July 31 2001 were included in the study. Patients were stratified into 3 groups (<= 65 years old, 66-75 years old, > 75 years old) and were compared, by both bivariate and multivariate analyses, to ascertain whether older critically ill patients had poorer hospital survival than younger patients. Results: Of 331 patients, 178 (53.8%) patients were ! 65 years old, 100 (30.2%) were 66-75 years old, and 53 (16%) were > 75 years old. Multivariate logistic regression analysis revealed that older age, presence of fatal comorbidities, mechanical ventilation, central venous catheterization, and higher acute physiology and chronic health evaluation score II (excluding the score obtained from age) were independent predictors of hospital mortality in the study population. Kaplan-Meier survival analysis revealed that patients <= 65 years old had better hospital survival than older patients (p=0.02). Conclusions: Older critically ill patients have poorer hospital survival than patients <= 65 years old, when other confounding factors such as disease severity score, invasive procedures and comorbidities were controlled for.