The author estimated the serum iron, serum copper and whole blood copper in hypoplastic anemia and obtained the following results: 1. The amount of serum iron markedly increased while that of serum copper slightly. This fact seems to suggest the disturbance in the iron utilization of the bone marrow. 2. In the course of the treatment of a patient suffering from hypoplastic anemia the change in the serum copper was proportional to but a little earlier than the serum iron; and the serum iron was in an inverse proportion to the hemoglobin content. 3. By the intramuscular injection of ACTH-gel, the quantity of serum iron clearly decreased, but that of serum copper had no significant change. 4. In the iron absorption and tolerance tests of hypoplastic anemia, it was found that the saturation point of serum iron was highly elevated and the rate of iron utilization was markedly decreased; and the alteration in the serum copper content was peculiar as compared with the normal. 5. The urine iron was evidently increased but the urine copper had no change. 6. In the fractional measurements of the visceral depot-iron of the patients died of hypoplastic anemia, every fraction, especially the fraction Ⅲ, of the depot-iron in the liver, spleen, kidney and bone marrow increased remarkably as compared with that in the case of other diseases. The increase in the visceral copper was especially pronounced in the liver.