The author studied changes in serum phosphatase and transaminase in the blood diease, especially leukemia, that had been diagnosed as suchmainly by bone-marrow tissue culture and a new hematological technique devised in the Hiraki Clinic of Internal Medicine, and obtained the following results. 1. In leukemia alkaline phosphatase is slightly decreased while acid phosphatase is slightly increased. However, only in monocytic leukemia these phosphatases are generally normal. In transaminase both glutamic oxalacetic transaminase and glutamic pyruvic transaminase are increased, but such increase is marked in acute myelogenous leukemia followed by monocytic leukemia and chromic myelogenous leukemia, while those in lymphocytic leukemia are normal....