Abstract: The diffusion chamber culture in vivo provides a nearly natural condition for the growth of cells. In the present study, the growth process of leukemic cells from 4 strains of leukemic mice (L615, L7212, L1210, P388) was observed dynamically. After a period of exponential growth, cell growth peak can be reached on the 6th or 7th day of culture, and the cell numbers were 5-14 folds of the inoculated cells. If anti-tumor agents were given to the recipients orally or intra-muscularly, the tumor cells would be affected in accordance with their sensitivity to the anti-tumor agents. The sensitivities of P388 leukemic cells cultured in diffusion chamber to Ⅱ anti-tumor agents were measured, results to simlar with the sensitivety in vivo were obtained.