The pharmacokinetics of cefmetazole, a new parenteral cephalosporin, administered intravenously and intramuscularly at a dose of 30 mg/kg to two groups of seven healthy volunteers were studied. Concentrations in serum were monitored over 8 h by a high-pressure liquid chromatography technique. The plasma concentration-time data were statistically fitted to a biexponential equation for both administration routes, and the data were analyzed by a two- and one-compartment kinetic model, respectively. For the dose range and the administration routes used, the pharmacokinetics of cefmetazole proved to be essentially linear, with clearances from plasma ranging between 3.8 and 12.5 liters/h. The mean maximum concentration in plasma after intramuscular administration of the drug was 90.1 micrograms/ml at 0.7 h. The elimination half-life, about 1.3 h, did not show statistically significant differences for the two routes of administration studied.