A total of 590 consecutive episodes of nosocomial bacteremia were prospectively followed in 30 intensive care units (ICUs) over a 9-month period. The crude and directly related mortality rates were 41.6% and 19%, respectively. The predominant pathogens were coagulase-negative staphylococci (24.4%) and coagulase-positive staphylococci (17.5%). The most frequent sources of infection were intravenous catheters (37.1%). Multivariate analysis defined seven variables as independently influencing crude mortality: adult respiratory distress syndrome (ARDS), septic shock, multiorgan failure (MOF), mechanical ventilation, chronic hepatic failure, acute renal failure, and APACHE II score of > or = 15 at diagnosis. Variables associated with a higher directly related mortality were septic shock, ARDS, acute renal failure, MOF, gram-negative or candidal bacteremia, source of bacteremia other than intravascular catheter, and severe sepsis. We conclude that preventing catheter colonization is crucial in reducing the incidence of bacteremia in an ICU, while improving outcome depends on better management of septic shock and associated complications.