Objective To study the effects of liver specific antigen（LSA）on liver allotransplantation rejection. Methods Orthotopic liver transplantation was performed in this study. GroupⅠ: syngeneic control（Wistar-to-Wistar）; GroupⅡ: acute rejection（SD-to-Wistar）. GroupIII: thymic inoculation of SD rat LSA day 7 before transplantation. The observation of general condition and survival time

rejection grades and the NF-кB activity of splenocytes were used to analyze severity of acute rejection and immune state of animals in different groups. Results The general condition of groupⅠwas fair post transplantation with no sign of rejection. All recipients of group Ⅱ died within days 9 to 13 post transplantation with median survival time of 10.7 ±1.37 days. As for group III

5 out of 6 recipients survived for a long period with remarkably better ge-neral condition than that of group Ⅱ. Its rejection grades were significantly lower than groupⅡ（P < 0.05）.NF-кB activity was only detected in groupⅠbetween days 5 and 7 after transplantation

whereas highactivity of NF-кB was detected at all points in group Ⅱ and low NF-кB activity was detected in group III which was significantly lower than that of group Ⅱ（P < 0.05）. Conclusions LSA is an important transplantation antigen directly involved in the immunorejection of liver transplantation. Intrathymic inoculation of LSA can alleviate the rejection of liver allotransplantation

grafts survive for a period of time thereby

allowing a novel way to liver transplantation immunotolerance.