T-lymphocyte depletion of the marrow graft can prevent graft versus-host disease(GVHD) effectively. T-lymphocytes of mice were transfected with high-titer (1.5×10⁵ CFU/ml) retrovirus supernatant, and by selection with G418 positive cell clones (T/pCD₂) were obtained. PCR and RT-PCR showed that CD gene was transferred into the T-lymphocyte and expressed successfully. T-lymphocyte and T/pCD₂ cells were exposed to different doses of 5-FCyt for various hours，and were then observed under light microscope and the viability of these cells was determined by MTT colorimetric cell proliferation assay. The results showed that retrovirus-mediated CD gene transferred to T/ pCD₂ cells could confer them high sensitivity to 5-FCyt, and T/ pCD₂ cells exposed to 5-FCyt (＞1 μmol/L) can be killed. But 5-FCyt was not harmful to normal T-lymphocyte cells. The survival time of T/ pCD₂ cells in the presence of 5-FCyt(3～5 d) was significantly shorter than that of T-lymphocyte(＞14 d).