Objective:To explore the safety and efficacy of immune checkpoint inhibitors(ICI)for patients with tumor recurrence after liver transplantation(LT).Methods:A single-center retrospective study was conducted for 6 recipients of tumor recurrence after LT on a therapy of ICI admitted into Shulan(Hang Zhou)Hospital from September 2015 to June 2018.The authors examined the occurrences of graft rejection and clinical outcomes of overall response rate, progression-free survival and overall survival after dosing of PD-1/PD-L1 inhibitors.Results:Six patients enrolled with tumor recurrence on a therapy of ICI undergoing LT due to hepatocellular carcinoma (HCC). Nivolumab (n=4) and duvalizumab (n=2) were administrated.The median session of treatment was 8.3(2-31) cycles.The disease outcomes were stable (3/6, 50%) and progressive (3/6, 50%), The progression-free survival time of 3 disease-controlled patients was 1.5, 16.2 and 18 months and the median survival time after recurrence was 19.75(10.8-37.8) months.Rejection occurred in 1 patients (1/6, 16.7%) and the occurring time of rejection was 28 days after PD-1 inhibitor dosing.After acute rejection, high-dose corticosteroids and immunoglobulin were ineffective and the patient died from acute rejection related liver failure.Conclusions:ICI may be employed as a salvage treatment for tumor recurrence after LT for HCC.Due to a possibility of severe acute rejection, usage should be cautious under close monitoring of liver function.