Vancomycin is widely used for the treatment of infections with Gram-positive bacteria in patients with end-stage renal disease. The concentration of vancomycin in serum, in ultrafiltrate, and in dialysate was measured during nine haemofiltration and seven haemodialysis procedures with high-permeability membranes. The t1/2 of vancomycin was 101 +/- 19 h in the interdialytic and interhaemofiltration period. There was no significant difference between the haemodialysis clearance (55.2 +/- 18.5 ml/min) and the haemofiltration clearance (66.8 +/- 13.6 ml/min). The redistribution phenomenon was about 25% in the post haemofiltration period and only 10% in the post haemodialysis period. Approximately 270 mg of vancomycin was recovered in dialysate or ultrafiltrate. With high-permeability membranes more commonly used in patients with end-stage renal disease, continuous monitoring of vancomycin therapy is recommended.