OBJECTIVE To evaluate the effects of newborn rat hepatocyte intrasplenic transplantation combined with rat augmenter of liver regeneration (rALR) injection in treating rats with acute hepatic failure. METHODS Acute hepatic failure (AHF) was induced in rats using D-gal (1.2 g/kg). The rats were then randomly divided into 6 groups. Group I received no further treatment and served as blank controls; group II received 1 ml buffered saline once through intrasplenic injection; group III received 1 ml rALR; group IV received 2 x 10(7)/ml hepatocytes; group V received 2 x 10(7) hepatocytes suspended in 1 ml rALR (50 microg/kg) and group VI received 2 x 10(7) hepatocytes in 1 ml cyclosporine A (10 mg/kg). The rats of the various treated groups were sacrificed at day 1, 5 and at week 2 and their livers and spleens were examined histopathologically. Blood samples of the rats were also obtained to determine the levels of TNF alpha and IL-1 beta. RESULTS There were no significant differences in survival between group I, II and III rats. 33.3% of the group IV rats survived for 2 weeks. At week 2, the survival rate of group V rats was significantly higher than that of group IV, but there was of no statistical significant increase when compared to that of group VI rats. Hepatocytes transplanted into spleens survived for 5-7 days in the spleens of group IV and VI rats, but they survived at least 2 weeks in group V. The average serum TNF alpha level in group IV was significantly higher than that in groups V and VI on the first postoperative day, but after four days, only the difference between group IV and group VI was significant (P < 0.05). The average serum level of TNF alpha in group II was higher than that in groups IV, V and VI on the first postoperative day (P < 0.05), but there were no significant differences between those in groups IV, V and VI on the 1st and the 5th postoperative days. CONCLUSIONS Newborn rat hepatocyte intrasplenic transplantation combined with rALR is effective in treating acute hepatic function failure induced by D-gal in rats. The transplanted hepatocytes can survive for at least 2 weeks in the spleens. The rALR mixed with the hepatocytes injected into the spleens may be able to facilitate the hepatocyte regeneration, to inhibit liver cell apoptosis and to suppress the cellular immunity.