Abstract Iron depletion is considered to be present when staining of bone marrow fragments for hemosiderin gives a negative result; anemia may be absent in that case. Several other methods of investigation which can render iron depletion probable are discussed. Iron depletion without anemia, especially in infants and women, seems to be quite common in affluent societies such as exist in North America and Western Europe. In these cases it is often transient, as is illustrated with some examples. It is also shown that in males who have been gastrectomized usually no anemia arises although iron depletion frequently develops. Women with iron depletion in the reproductive age, however, run a rather great risk of developing irondeficiency anemia because of menstrual blood loss and pregnancies. In iron depletion without anemia, a decrease of iron-containing enzymes has been found in some tissues; it has not been demonstrated, however, that this decrease has any pathological significance. Neither has it been shown that iron depletion as such causes clinical symptoms. Until now no practical methods have been developed to artificially enrich food elements satisfactorily with iron. At present the best way to prevent iron-deficiency anemia in women, particularly in pregnancy, seems to be to strive for a well-balanced diet with an adequate amount of iron-rich constituents. In pregnancy, however, regular controls of the blood picture remain necessary to ensure early diagnosis and adequate treatment of anemia.