As more studies are done on the iron status of athletes, the significance of apparent iron deficiency remains controversial. Do observed changes in iron status in athletes indicate an actual iron deficiency or a physiological response to exercise? Iron replacement would clearly be indicated if an iron deficiency was present but would not be necessary or effective if the observed changes were simply a physiological response. There is agreement that serum ferritin and haemoglobin decrease with some exercise conditions and that some indicators of haemolysis, such as serum haptoglobin and bilirubin, change in response to exercise. Expansion of plasma volume and the shift of iron storage from bone marrow to the liver could support the claim that the apparent reduced iron status parameters occurring with exercise are misleading. Countering this concept are studies in athletes which demonstrate dietary iron intake deficiencies and blood loss in the gastrointestinal and urinary tract. Iron deficiency is common in the general population, particularly in women. Therefore, continued monitoring of iron status in athletes appears justified in the face of present knowledge. Replacement therapy, when iron deficiency is apparent, is recommended.