1. The urinary excretion of uric acid was studied in 17 normal subjects and in 38 patients with leukemia. The mean excretion of uric acid by the normal subjects was 6.5 mg./Kg. of body weight /24 hrs. The mean excretion of uric acid in 14 patients with acute lymphoblastic leukemia was 30.3 mg./Kg. /24 hrs.; in 13 patients with acute myeloblastic leukemia, 13.0 mg.; in 6 patients with chronic lymphocytic leukemia, 5.2 mg.; and in 5 patients with chronic myelocytic leukemia, 13.5 mg.
2. Following therapy with cortisone, 6-mercaptopurine or Amethopterin, the urinary excretion of uric acid increased in the cases of acute leukemia as the leukocyte count declined. As the leukocyte count approached normal levels, the uric acid excretion decreased. The urinary excretion of xanthine and guanine paralleled the excretion of uric acid.
3. In association with the administration of an aromatic nitrogen mustard derivative to one patient with chronic lymphocytic leukemia and Myleran to one patient with chronic myelocytic leukemia, there was only a slight increase in uric acid excretion.