The Chromosomal abnormalities were studied on 38 patients, who suffered from acute myelogenous leukemia, lymphocytic leukemia, monocytic leukemia, wrythroleukemia, chronic myekigenous leukemia, aplastic anemia, sideroblastic anemia and malignant lymphoma. The results were as follows. A case of acute myelogenous leukemia and two cases of acute monocytic leukemia showed pseudodiploid of karyotype. A case of acute myelogenous leukemia showed the mode of chromosome number bimodal in 46 and 47. Four cases of chronic myelogenous leukemia had ph1 chromosome. Four cases of malignant lymphomashowed abnormal karyotypes respectively. Majority of acute lymphocytic leukemia, eryrhroleukemia and aplastic anemia showed normal karyotypes. These findings are discssed in relation to the significance of chromosomal abnormalities in leukemia and related malignant diseases.