A single intravenous 15 mg/kg dose of cefamandole was given to 6 patients in chronic renal failure before hemodialysis, and 3 were examined during an interdialysis period. Mean cefamandole clearance by hemodialysis was 24 +/- 12 ml/min; 35 +/- 15% of the dose was recovered in the dialysate. The cefamandole half-life (1 1/2) on dialysis was 4.0 +/- 0.29 hr; off dialysis it was 13.9 +/- 4.2 hr. High urine concentrations of cefamandole in these patients suggests usefulness in urinary tract infection.