Abstract: Objective: To investigate expression of the novel membrane molecule p140 on activated T cell in the patients after liver transplantation. Methods: Immunofluoescence staining and FCM analysis were utilized to monitor the expression of p140,and transplanted liver biopsy employed to distinguish the allograft acute rejection. Results: it express weakly on T cell in the patients after liver transplantation,and express remarkably while they develop allograft acute rejection. Conclusion: P140 is transplanted antigen induced T cell activated antigen,and is one of credible and specific guideline to distinguish and monitor allograft liver transplantation.