移植排斥（英语：transplant rejection）是器官移植器官并不被受移植者身体接受的情况。一般来说这是因为免疫系统攻击移植器官所引起的。免疫系统攻击体内的异物，如病毒或细菌。通过分析贡献者和接受者的血清型并配对或服用免疫抑制剂可以减少排斥反应。

Transplant rejection occurs when transplanted tissue is rejected by the recipient's immune system, which destroys the transplanted tissue. Transplant rejection can be lessened by determining the molecular similitude between donor and recipient and by use of immunosuppressant drugs after transplant.