We investigated the pharmacokinetics of cefmenoxime (CMX) administrated to renal-failure patients undergoing continuous arteriovenous hemofiltration (CAVH). CAVH was carried out with a filter (0.5 m2) employing a PAN-50P (hollow fiber type) made of polyacrylonitrile membrane, with a blood flow rate of 100 ml/min and a filtration rate of 1,200 ml/hr. At 5 and 300 minutes after the CMX administration, the concentrations of CMX in the serum were 126.8 mg/L and 31.5 mg/L, respectively. The T1/2 beta was 3.55 hours. In 300 minutes after the administration of CMX, the total amount of CMX contained in the filtrate corresponded to 11.6% of the administered dose.