Results concerning morphological and biochemical changes following intravenous administration of different doses of acetaminophen in dogs are reported. Acetaminophen infusion, as a parenteral solution (500 mg per kg per 90 min), produced fulminant hepatitis characterized by a good correlation between Portmann's grade of lesion and percentage of necrosis. All animals died within 76 hr after intoxication. Analysis of biochemical parameters revealed positive correlation between serum bilirubin levels and severity of the hepatic lesion. The experimental model of acetaminophen-induced hepatotoxicity is proposed as a model for evaluation of the therapeutic efficacy of new medical and surgical procedures.