Objective:To evaluate the expression of CXCR4 and the migration rate of bone marrow stromal CD34+cells in differ-ent risk groups with myelodysplastic syndromes (MDS) using correlation analysis. Methods: Forty MDS patients were divided into low-and high-risk groups based on the International Prognosis Scoring System (IPSS). The former was composed of 20 patients with IPSS<1.5, whereas the latter was composed of 20 patients with IPSS≥1.5. Bone marrow (BM) samples of these patients and 10 nor-mal controls were collected. CD34+cells were separated and purified. The expression of CXCR4 was determined by flow cytometry. The migration rate of CD34+cells on the chemotactic effect of SDF-1αand on the effect of bone marrow stromal cells were measured. Results:The expression rate of CXCR4 was higher in the high-risk MDS group than in the low-risk and control groups (P<0.000 1). No significant differences existed between the low-risk and the control groups (P>0.05). The migration rate of CD34+cells on the ef-fects of SDF-1αand marrow stromal cells were significantly increased in the high-risk MDS group compared with those in the low-risk and control groups (P<0.000 1). Migration rate of CD34+cells on the effect of marrow stromal cells was positively correlated with CX-CR4 expression (P=0.000 1). Conclusion:The CXCR4 expression and migration rates of CD34+cells on the effect of marrow stromal cells are significantly higher in the high-risk MDS group than in the low-risk group. Migration rate has a positive correlation with the CXCR4 expression, which further indicates that MDS is a heterogeneous group of hematopoietic stem cell malignancies. The expres-sion and function of SDF-1 and its receptor CXCR4 differ within each group with various risks. SDF-1 and CXCR4 may be involved in MDS pathogenesis.