The diagnosis of bacteremia in critically ill patients is classically based on fever and/or leukocytosis. The objectives of this study were to determine 1) if our intensive care unit obtains blood cultures based on fever and/or leukocytosis over the initial 14 days of hospitalization after trauma; and 2) the efficacy of this diagnostic workup. An 18-month retrospective cohort analysis was performed on consecutively admitted trauma patients. Data collected included demographics, injuries, and the first 14 days maximal daily temperature, leukocyte count, and results of blood and catheter tip cultures. Fever was defined as a maximum daily temperature of 38.5 degrees C or greater and leukocytosis as a leukocyte count 12,000/mm3 or greater of blood. Five hundred ten patients were evaluated for a total of 3,839 patient-days. The mean age and injury severity score were 49 +/- 1 years and 19 +/- 1, respectively. Four hundred twenty-five blood culture episodes were obtained and 25 (6%) bacteremias were identified in 23 patients (5%). A significant association was found between obtaining blood cultures in patients with fever (relative risk [RR], 7.7), leukocytosis (RR, 1.3), and fever + leukocytosis (RR, 3.2). However, no significant association was found between these clinical signs and the diagnosis of bacteremia. In fact, fever alone was inversely associated with bacteremia. Our intensive care unit follows the common "fever workup" practice and obtains blood cultures based on the presence of fever and leukocytosis. However, fever and leukocytosis were not associated with bacteremia, suggesting inefficiency and that other factors are more important after trauma.