Abstract: Objective:We studied the peripheral blood leukemic cell DNA, cell cycle and CD44changes of acute leukemia. blast crisis of CML and MDS--RAEB Patients to find their relationship with clinical feature in order to guide the clinical diagnosis and treatment. Methods :By using FCM, the DNA index. DNA ploidy and SPof 46 acute leukemia.10blast crisis of CML.5 MDS--RAEB patients and also blood CD44 expressions were studied in the above patients. Results: There was difference of DNA aneuploidy in acute leukemia.blast crisis of CML and MDS--RAEB Patients i DNA aneuploidy was higher in radical/relapsed acute leukemia patients than that of CR acute leukemia patients. The treatment of acute leukmia patients with diploids and lower DNA index was more effective. There was no difference of blood CD44 expression between patients and urinal controls. Conclusion =DNA index and aneuploidy may be regarded as an important reference in giving chemotherapy regimens of acate leukemia.