To improve the effect of chemotherapy of chronic myelogenous leukemic(CML) in blastic phase, the following clinical analysis were conducted. 1) The present study consisted of 53 adult patients with CML, who were registered to the 2nd Department of Medicine, Okayama University Hospital and diagnosed as blastic phase between from January 1970 to March 1980. There were 29 males and 24 females, and age ranged from 15 to 77 years (median: 41). 2) These 53 patients were divided into 4 groups. i) Group I-A (5 cases) was diagnosed as blastic crisis(BC) with hiatus leukemicus(HL) and initially treated with multicombination chemotherapy such as NCD, DMP or NCDP regimens (N: Neocarzinostatin, C: Cytosine arabinoside, D: Daunorubicin, M; 6-Mercaptopurine, P: Prednisolone). ii) Group I-B (16 cases) was diagnosed as BC with HL and initially treated with VP or VPM regimens (V: Vincristine, P: Prednisolone, M: 6-Mercaptopurine). iii) Group II-A (11 cases) was early diagnosed as BC without HL according to our established criteria, and initially treated with multicombination chemotherapy such as NCMP, DCMP, NDMP, NCDP or NCDVP. and, iv) Group II-B (21 cases) was early diagnosed as BC without HL and initially treated with VP, MP, or VPM. 3) Complete remission(CR) rate of each group was 20.0% in Group I-A, 56.2% in Group I-B, 27.3% in Group II-A and 47.6% in Group II-B. 4) Median survival and its surviving ranges after BC of each group were 3.6 months (1.8-4.5), 6.7 (1.0-24.2), 6.0 (2.6-22.8) and 13.0 (4.1-43.5). Median survival of CR-responders was 3.6, 10.0, 8.7 and 17.0 months, respectively. 5) The rate of one-year survivors of each group was 0%, 31.3% 9.1% and 52.4%. 6) In conclusion, the most ideal approach to prolongation of the survival period of CML patients after entering BC is i) to diagnose BC as early and accurate as possible, and ii) to treat these patients initially with rather mild regimens such as VP or VPM, instead of aggressive regimens with multicombination drugs.