1. Iron metabolism has been investigated in patients suffering from chronic renal failure, using a whole body monitoring technique. 2. Absorption of labelled inorganic iron was decreased. 3. Radio-iron was lost from the body at a rate comparable to that found in normal subjects. 4. The red cell incorporation of radioactive iron was diminished. 5. The results suggest that anaemia in these patients was due to decreased erythropoiesis and not due to iron deficiency despite the evidence of markedly abnormal iron handling presented.