IN previous experiments1,2, a rise in serum glucose, and increased endogenous gluconeogenesis in liver slices, was found 5 min after the injection of 50–100 mg of 2-deoxy-glucose (2 DG), an inhibitor of glucose utilization, into fasting rats. 2 h after administration of 2 DG, an accumulation of liver glycogen was observed. There was a constant rise in urea excretion during the first 24 h. Adrenalectomy inhibited the response to 2 DG, and no effect was observed when 2 DG was injected together with glucose or insulin.