AIM:To explore the expression of perforin and granzyme B genes mRNAto judge the effect of immunosuppression in acute rejection of liver transplantation.METHODS: The expression of perforin and granzyme B genes mRNA was examined by reverse transcription-polymerase chain reaction (RT-PCR) in hamster to rat liver grafts under the immunosuppression of cyclosporine or/and splenectomy. Histological findings were studied comparatively.RESULTS:Cyclosporine could obviously decrease the cellular infiltration, and completely repress the expression of mRNA for perforin and granzyme B, but could not change severe hepatocyte necrosis and hemorrhage. Splenectomy could significantly lighten hepatocyte necrosis, and completely eliminate hemorrhage,but not affect the cellular infiltration and the expression of perforin and granzyme B genes mRNA. Cyclosporine or splenectomy alone could not prolong the survival time, however, their combination could completely repress the rejection of liver grafts. The survival time of animals were significantly prolonged (37.1 days). The architecture of hepatic lobules was preserved. There were slight cellular infilt-ration in the portal tracts and no expression of perforin and granzyme B genes mRNA could been seen in three weeks after transplantation.CONCLUSION:Perforin and granzyme B genes are valuable in judging the effect of immunosuppression in liver transplantation.