The pharmacokinetics of vancomycin were evaluated in 34 patients (10 burn patients, 14 intravenous drug abusers [IVDA], and 10 controls). Multiple serum samples were drawn following a 1-h vancomycin infusion at steady state over an 8- to 12-h dosing interval. Pharmacokinetic parameters were derived by noncompartmental analysis. There were no significant differences among the groups with respect to age, weight, serum creatinine, volume of distribution, or protein binding. Burn patients had a significantly higher creatinine clearance than did IVDA or controls. Vancomycin clearances averaged 142.8, 98.0, and 67.7 ml/min in burn patients, IVDA, and controls, respectively. The renal clearance of vancomycin was also higher in burn patients than in the other groups. IVDA tended to have a higher vancomycin clearance (31% higher) than did controls, but the difference was not statistically significant. Vancomycin clearance was much higher in burn patients requiring dosage individualization and close monitoring. A considerable amount of vancomycin was eliminated through renal tubular secretion, making dosage predictions based on creatinine clearance more difficult. Further work with IVDA will be needed to determine if they represent a group requiring aggressive vancomycin dosages.