Abstract： Objective To study the relationship between graft-versus-host disease (GVHD) and endothelium injury following hematopoietic stem cells transplantation in mice. Methods C57BL/6 mice as donors and Balb/c mice as recipients were randomly divided into 4 groups: control group, bone marrow transplantation group, GVHD group, GVHD mitigation group. The clinical manifestations,circulating endothelial cells and tissue pathological changes were observed at different time points after transplantation. Results No manifestations of GVHD were found in each group at the day 5, while those were found in GVHD group at the day 9 and all died within 15 days. The counts of endothelial cells in peripheral blood showed no significant difference at the day 5 between GVHD group (7. 34 ±1.26 cells/μl) and bone marrow transplantation group (11.51 ± 7. 40 cells/μl) or GVHD mitigation group (7. 36 ± 0. 16 cells/μl), while among three groups there was statistically significant difference at the day 9 (GVHD group: 153. 64 ± 35. 35 cells/μl vs bone marrow transplantation group: 10. 49 ±5. 61 cells/μl and GVHD mitigation group: 47. 82 ± 4. 69 cells/μl). The scores of pathological aGVHD had no significant difference at the day 5 between GVHD group (4. 33± 1. 53) and bone marrow transplantation group (3. 33 ± 0. 58) or GVHD mitigation group (4. 00 ± 1.73), while among three groups there was statistically significant difference at the day 9 (GVHD group: 10. 0 vs bone marrow transplantation group: 3. 33 ± 1.15 or GVHD mitigation group: 4. 33 ± 0. 58) and at the day 14 (GVHD group: 10. 33 ± 2. 58 vs bone marrow transplantation group: 2. 33 ± 1.25 or GVHD mitigation group 3. 33 ± 1.15). Conclusion Occurrence of GVHD causes endothelial damage again and injured endothelium worsens the GVHD.