Solid organ transplantation is the most effective treatment for end-stage organ failure.However,post-transplant rejection can damage the transplanted organ and reduce the survival time of the transplant.In recent years,liquid biopsy has become an important means for detecting and diagnosing rejection reactions,with particular attention paid to the study of exosomes.As biomarkers,exosomes have the advantages of being non-invasive and highly accurate in diagnosis,and can be used to diagnose transplant rejection.This article reviews the research progress of exosome detection in alloge-neic organ transplant rejection,including kidneys,lungs,hearts,livers,etc.