Abstract: Objective 　To investigate the dist ribution and clonality of TCR Vαsubfamily T cells in patients with chronic myeloid leukemia (CML) . Methods 　The CDR3 size of TCR Vα 29 subfamily genes was amplified in peripheral blood mononuclear cells from 10 cases with CML using RT-PCR, to observe the usage of TCR Vα repertoire, the PCR products were further analyzed by genescan technique for detection of the CDR3 size, to evaluate clonality of TCR Vα T cells. Results 　1～21 Vα subfamily T cells could be identified from different samples in CML cases, predominantly in Vα3, 4, 8, 10, 14. Oligoclonal (clonal expansion) T cells were identified in Vα1, 2, 3, 4, 5, 8, 10, 12, 14, 15, 16, 19, 21 and 23 subfamilies. Conclusion 　The selected usage and clonal expansion of TCR Vα subfamily T cells from peripheral blood could be found in patients with CML, it may be related to CML associated-antigen. Distribution of Vα subfamily clonal expansion displays individual specificity.