Six consecutive patients treated with intraperitoneal vancomycin for catheter infections developed cloudy dialysate in the exchange to which the drug was added. In all six patients, the dialysate was clear before the addition of vancomycin. All had elevated dialysate leukocyte and polymorphonuclear counts after the intraperitoneal vancomycin. All had sterile cultures. Two continued to have cloudy dialysate while continuing on 500 mg vancomycin per one exchange per day. In one of these patients, the catheter did not appear infected when removed. All episodes occurred after we had changed from Lilly's Vancocin to Lederle's Vancoled. During this time, the per cent of peritonitis episodes with sterile cultures rose from 0% in the previous 3 months to 50%. In all episodes with sterile cultures Vancoled had been administered via the dialysate. Fourteen patients had received intraperitoneal Vancocin in the previous nine months for the same indications; none developed cloudy dialysate. We believe that these cases represent chemical peritonitis due to Vancoled.