The purpose of this study was to observe the chimera status of 15 patients received allogeneic hematopoietic stem cell transplantation by using STR-PCR method. DNA from peripheral blood or bone marrow of donors and recipients in different time were extracted, 5 STR loci with high polymorphism were amplified by PCR. The PCR products were analyzed by PAGE and silver staining. The results showed that 15 patients had different level of engraftment. 10 patients displayed complete chimerism, five patients showed mixed chimerism. 10 patients were keeping continuance of remission, 4 patients died and one patient relapsed but still alive. The decrease of donor DNA amounts in mixed chimerism foreshowed the early graft rejection or relapse. Incidence of I-II degree aGVHD high significantly correlated with mixed chimerism. It is concluded that STR-PCR is the sensitive and accurate method for analyzing the chimera status after allogeneic hematopoietic stem cell transplantation. Mixed chimerism is a prophetic role for leukemia relapse and chimera status guides the treatment.