We determined the intraoperative concentrations of cefmetazole and cefoxitin in serum and muscle from the wound of 30 patients who were undergoing cholecystectomies. The study employed an open-label design in which all patients randomly received cefoxitin sodium (30 mg/kg) or cefmetazole sodium (15 or 30 mg/kg) intravenously with the induction of anesthesia. Total serum and wound-muscle concentrations achieved with cefmetazole 30 mg/kg were significantly greater than those achieved with a similar dose of cefoxitin. Cefmetazole in a 15 mg/kg dose was comparable with cefoxitin 30 mg/kg in achieved concentrations. The elimination half-life for cefoxitin was much shorter than that for cefmetazole (41 min v. 64-68 min, respectively) and this relates to a shorter duration of action for the former. The choice of agent for surgical prophylaxis should incorporate factors relating to drug pharmacokinetic properties as well as microbiological factors.