Pharmacokinetics of teicoplanin (TP) was assessed in critically ill patients on continuous veno-venous hemodiafiltration (CVVHDF), in 18 cases, after the third dose in repeated administration. The TP peak concentration amounted to 28.7±18.6 μg/mL and trough concentration 9.7±6.5 μg/mL, the half-life 101.6±40.2 h, the volume of distribution 1.5±0.7 L/kg and the TP clearance 0.2±0.1 ml/h/kg. The dose of CVVHDF was 32.1±7.0 mL/Kg/h. There is significant variability in trough concentrations in critically ill patients receiving CVVHDF, which did not only appear to be influenced by effluent flow rate. Here, empirical dosing of teicoplanin failed to achieve the target trough concentration in 87.5% of 18 cases. Therapeutic drug monitoring is indispensable.