The efficacy of teicoplanin in the treatment of peritonitis in patients undergoing continuous ambulatory peritoneal dialysis (CAPD) was evaluated in a randomised comparison with vancomycin. The dosage regimen used was 50 mg of vancomycin or teicoplanin per 2 1 bag of dialysate for 48 h followed by 25 mg per bag for a further five days. Twelve episodes of peritonitis were studied. There was no significant difference in the bacteriological or clinical cure rates of either antibiotic.