Abstract: 32 specimens of leukemic patients’bone marrow cells with 8 cases of normal controls were studied by means of an in vitro BrdU chromosome-labeling method for cellular growth kinetics.41 blood specimens of patients with leukemia and 30 normal controls were studied for the same purpose to investigate the percentages of M₁, M₂ and M₃. Our experimental data revealed that the percentage of M₁ of leukemic sample was higher than that of the normal controls,showing that the growth rate of the bone marrow cells and blood cells was apparently slower with statistical significance.The variation of the percentage of M-1 was statistically positively related with the percentage of the blastic young cells in the bone marrow,as well as that of the number of aneuploid cells in leukemia.It suggested that this kind of research study might serve as a sensitive parameter for the early diagnosis of leukemia.The percentage of M₁ would drop down to approach normal levels during remission after treatment when the chemotherapy was effective.It proposed that the study of growth kinetics of bone marrow and blood cells by means of BrdU chromosome-labeling method in vitro might predict the effect of the chemotherapy and on the other hand,advocate the relapse.It seemed to be a sensitive test for estimating the patient’s prognosis.All the laboratory data were treated statistically by means of Cromemco Computer after establing soft ware using the Basic Language.