The prognostic value of several clinical and hematologic features, recorded at diagnosis, in chronic phase Ph1 positive chronic myelocytic leukemia (CML), was analyzed in 135 patients using life-table analysis. About one third of patients were atomic bomb survivors and they had been examined twice a year before the diagnosis of CML. In general, features representing tumor cell burden, i.e., leukocyte count, spleen sizes, and absolute differential cell counts of all granulocyte series cells except myeloblasts affected survival significantly, while sex, age, hemoglobin, platelets and features representing quality of leukemia, i.e. neutrophils alkaline phosphatase score, percent Ph1 positive cells in bone marrow, and percent differentials of all granulocyte series cells except promyelocytes and segmented neutrophils were all insignificant. Multivariate life-table analysis was also performed using age, sex, hemoglobin, platelets, and leukocyte count as predictor variables. The result was that leukocyte was the single most important factor in this analysis and annual death rates between low risk (risk ratio less than 0.8) and high risk (risk ratio greater than 1.4) differed considerably up to four years from diagnosis, indicating our formula to calculate risk ratio is valid as a grading parameter of chronic phase Ph1 positive CML within four years from diagnosis.