We compared retrospectively vancomycin and teicoplanin trough serum levels after loading doses and, subsequently, after high daily doses, in 52 patients (26 in each group) who had developed infections after implantation of an orthopedic device. The target trough serum level was > 25 mg/l. Trough levels were significantly higher at 2 days (±1) and 5 days (±1) in patients who received teicoplanin compared with patients who received a continuous perfusion of vancomycin (26.1 vs. 16 mg/l at day 2 ± 1, P = 0.01; 27.8 vs. 19.9 mg/l at day 5 ± 1, P = 0.01). One of the 26 patients taking vancomycin reached the target trough serum level by day 2 (±1), whereas 10 of the 26 patients taking teicoplanin reached the target by that time (P = 0.002). At day 5 (±1), 6/26 patients taking vancomycin reached the target, versus 13/26 patients taking teicoplanin (P = 0.04). However, physicians should remain cautious when administering teicoplanin empirically because of the higher MIC₉₀ values observed for coagulase-negative staphylococci compared with vancomycin.