Abstract: Objective To investigate the clinical signifi cance of MVD, change in EPCs number in peripheral blood and bone marrow, and the expression of VEGFR-2 in bone marrow biopsy specimens of patients with acute myeloid leukemia (AML). Methods The number of EPCs was determined by FCM method in 30 patients with AML and 10 healthy cases in control group. Bone marrow pathological sections of 30 AML patients were embedded by conventional paraffi n. Microvessel density(MVD) and the expression of vascular endothelial growth factor receptor-2(VEGFR-2) were detected by immunohistochemistry assay and its relationship with clinical features was analyzed. Results (1)The number of EPCs in the peripheral blood （PB）and bone marrow（BM）of patients with AML before treatment was signifi cantly higher than that in control group( P<0.01). After treatment, the number of EPCs of AML patients in CR group was signifi cantly lower than that in NR groupP<0.01(PB); P<0.05(BM).(2) MVD and VEGFR-2 expression were signifi cantly higher than that in control group(P<0.05). Tested by spearman rank correlations, the absolute numbers of EPCs in PB and BM had positive correlation with MVD and VEGFR-2 P<0.01(PB); P<0.05(BM). (3) The survival curves for 100 weeks had signifi cant difference between groups of >20/μl and <20/μl of EPCs. (4) By Cox regression, there were risk factors including the absolute number of EPCs before treatment, the percentage of WBC, VEGFR-2 and β2-MG. Megakaryocytic cells and ECOG performance status were protective factors. Conclusion Dynamic observation of EPCs count combined with MVD and VEGFR-2 may be clinically correlated with the evaluation of AML vascular endothelial function in a certain degree. It may be used to evaluate the treatment outcomes and act as a prognostic marker for AML.