The aim of this study was to investigate the effects of hepatic and renal failure on the pharmacokinetics of flunixin in carbon tetrachloride (CCl(4))- and glycerol-treated rats. After intravenous administration of flunixin (2 mg/kg), the plasma concentration of flunixin was measured by high-performance liquid chromatography. Both acute hepatic and renal failure resulted in significantly increased area under the curve (AUC), prolonged elimination half-life (t(1/2β)), and reduced total body clearance (Cl(tot)) compared with respective controls (P<0.05). In conclusion, hepatic failure as well as renal failure modified the pharmacokinetics of flunixin.