We made clinical statistical observations of the 8 cases of chronic lymphoid leukemia admitted to our clinic during the period of 16 years from 1952 to 1967, and obtained the following results. 1. Five out of the 8 cases were in advanced age of over 55 years old of which the ratio of male to female was 3:1. 2. We found no noteworthy episode in the family of the patients but one of the 8 cases proved to have had a secondary atomic bomb irradiation (i.e. irradiation after the bomb explosion). 3. In our various examinations of the patients to their history, symptoms and others, the results were approximately similar to those reported in JAPAN and other countries previously. 4. The growth pattern of lymph node tissue culture in all cases was similar to those of bone marrow in patients with acute lymphocytic leukemia. However, the growth zone was mainly consisted of mature small lympocytes. 5. The growth pattern of bone marrow in 7 out of 8 cases was similar to those of bone marrow in patients with chronic myelogenous leukemia (i.e.: double zone). However, the inside of double growth zone was mainly consisted of mature lymphocytes densely and the outside a small number of granulocytic cells.