Current guidelines for the empiric treatment of ventilator-associated pneumonia (VAP) recommend that vancomycin is dosed 15 mg/kg and administered twice daily for a target trough level of 15 to 20 μg/mL. This study compared conventional intermittent vancomycin infusion (IVI) with continuous vancomycin infusion (CVI). Our prospective, randomized study compared CVI with IVI in trauma patients with suspected VAP. The primary outcome measure was a serum vancomycin level within the target level 48 hours after initiation of therapy. Treatment groups were compared using standard statistical methods. The study included 73 patients, 36 IVI and 37 CVI. Eighteen patients were withdrawn from the study as a result of discontinuation of the drug before 48 hours or failure to draw levels at the appropriate time, resulting in 27 IVI and 28 CVI study patients. There were no differences between treatment groups in gender (P = 0.97), Injury Severity Score (P = 0.70), total body weight (P = 0.36), or age (P = 0.81). The mean serum vancomycin level for the IVI group was 8.9 ± 3.9 μg/mL, and the CVI level was 19.8 ± 6.13 μg/mL (P < 0.0001). Two patients in the IVI group (7.4%) were in the therapeutic range compared with 16 (57.1%) in the CVI group (P < 0.0001). Six patients in the CVI group (21.4%) and none of the IVI patients had supratherapeutic levels. Four patients developed renal insufficiency, three IVI (11.1%) and one CVI (3.6%) (P = 0.36). The current American Trauma Society dosing recommendations for vancomycin for presumptive VAP treatment are inadequate. Continuous vancomycin infusion should be adopted as the standard dosing strategy.