Acute liver failure after extensive hepatic resection constitutes a major cause of morbidity and mortality especially in 
patients with preexisting liver diseases. Although liver transplantation has been suggested as the most effective treatment of patients with acute liver failure, a variety of technical, functional and logistic obstecles limits its application. Hepatocyte transplantation is a new option for treatment of patients with acute liver failure. In the present study hepatocyte transplantation has been investigated by evaluation of the clinicopathological and laboratory effects in 56 rats with surgically induced acute liver failure by 90% hepatectomy. Rats were divided into two groups: group I transplanted rats including 30 rats in which intrasplenic hepatocyte transplantation has been performed 48 hours before 90% hepatectomy and group II including 26 rats in which no hepatocytes have been transplanted before hepatectomy. Comparison between both groups revealed a significant increase in the weight of the remaining liver mass in group I transplanted rats. There was also a significant improvement in the level of glucose, bilirubin and alanin transferase (ALT) while there was a tendency to improve in the level of albumin and prothrombin time in the same group. Moreover, group I transplanted rats showed a significant prolonged survival time and more long term servivors in relation to the non transplanted group. This clearly demonstrates that hepatocyte transplantation markedly improves the physiological function and regenerative capacity of the remaining liver mass after surgically induced acute liver failure by 90% hepatectomy. Thus hepatocyte transplantation can participate effectively to solve the problem of acute liver failure that may eliminate or even minimize the increasing demands for orthotopic liver transplantation.