The Pathological lesions due to oral administration of different daily doses I.e. 0.062, 0.125, 0.250, 1, 2.5 and 5 gram per kg B.W. (Body Weight) of acetaminophen in the liver of rat and also changes in serum levels of AST (Aspartate aminotransfrase) and ALT (Alanine amino transfrase) were studied. No lesions were observed in rats received 0.062 and 0.125 g/kg B.W of acetaminophen where as the rats received higher doses than
0.125 g/kg B.W. showed severe lesions which were dose dependent and based on the post treatment interval. The main lesions included passive congestion , cell swelling, granular degeneration, hemorrhage, mild to severe centrilobular coagulative necrosis, moderate to severe vacuolar degeneration in the midzonal and periportal hepatocytes, regenerative activity and macrophage infiltrations. There was evidence of hydropic vacuolation by Sudan and PAS (Periodic acid Schiff) staining in the surviving hepatocytes with vacuolar degeneration. There were eosionophilic intranuclear inclusion bodies in the surviving hepatocytes that cold be as a path gnomonic lesion. The serum levels of AST and ALT with doses of 0.062 and 0.125 g per kg B.W. showed no significant increase in their levels as compard to control ones, however, a significant increase (P < 0.05) was noted in the animals which received higher doses and it corraborated with the microscopic lesions in the liver.