Objective To study the relationship between the expression of perforin, granzyme B and the cytotoxicity of NK cells, after NK cells were purified and expanded with different cytokines. Meth-otis It was detected that the mRNA expressions of perforin, ganzyme B from 8 donors, and the cytotoxcity of NK cells to target I(562 cells by competitive qualitative RT-PCR. Results The mRNA expressions of perforin, granzyme B by purified and expanded NK cells with different cytokines were markedly enhanced, and IL-2 +IL-15 group, IL-2 + IL-12 + IL-15 group were significantly higher than others. It is consistent that the relationship between the mRNA expressions of NK cells and the cytotoxicity of NK cells to I(562 cells. Conclusion The mRNA expressions of perforin, granzyme B of NK cells with different cytokines were obviously.