With the sternal bone marrow obtained from various leukemias definitely diagnosed by their bone-marrow tissue culture the author measured the glycolysis in the sternal bone marrow and obtained the following results. 1. Anaerobic glycolysis of 0.2 cc/hr sternal bone marrow in leukemia is markedly increased as compared with that in normal persons, and the grads of such an increase differs according to the form of diseases. Pointing out the form of leukemias from the greater to the lesser acceleration in the anaerobic glycolysis, they are in the order of acute lymphocytic leukemia, acute myelogenous leukemia, monocytic leukemia, chronic myelogenous leukemia and chronic lymphocytic leukemia. 2. The acceleration of X(M)(N)(2)/K is most marked in acute myelogenous leukemia followed by monocytic leukemia, and in chronic myelogenous leukemia it is close to the normal value, while in lymphocytic leukemia it is less than the normal value. In the case with a higher percentage of immature cells there is an increasing tendency in X(M)(N)(2)/K. 3. With a single exception of chronic lymphocytic leukemia Q(M)(N)(2) is accelerated in every form of leukemia, and in pointing out the ones with marked acceleration and down they are in the order of acute lymphocytic leukemia, acute myelogenous leukemia, monocytic leukemia, and chronic myelogenous leukemia. Moreover, those with greater number of nucleated cells and a higher percentage of immature cells in bone marrow the value of Q(M)(N)(2) tends to be greater. 4. The aerobic glycolysis in leukemia does not show any marked difference from that in arachnoiditis adhaesiva, idiopathic ardiaspasmus, diabetes mellitus, hookworm disease, hypoplastic anaemia and Banti's syndrome. 5. The ratio between the oxygen consumption and anaerobic glycolysis (Q(M)(N)(2)/Qo(2)), though less than that in malignant tumor, is higher than normal. This increase is especially marked in acute leukemia but slight in chronic leukemia, and in monocytic leukemia it is intermediate between the acute leukemia (myelogenous and lymphocytic) and the chronic leukemia (myelogenous and lymphocytic). Namely, the anaerobic glycolysis in the leukemic bone marrow is accelerated as compared with that in normal bone marrow, but the grade of such an increase differs according to the form of diseases; and it is most prominent in acute leukemia; relatively slight in chronic leukemia; and it is intermediate between the acute and the chronic in monocytic leukemia. The value of Q(M)(N)(2)/O(2) indicates that the metabolism of leukemia is intermediate between the normal bone marrow and that in malignant tumor.