Use of erythropoietin (EPO) therapy and iron supplementation has improved the management of anemia in patients with end-stage renal disease (ESRD). As more patients receive supplemental iron, however, concerns are being raised about a potential link between iron and infection. There is biologic plausibility for this link, since iron is a growth factor for bacteria and certain host defense mechanisms are iron-sensitive. Animal models show that injection of iron leads to increased susceptibility to bacterial infection. In some studies, patients with high serum ferritin levels have reduced neutrophil function. However, these studies did not determine whether serum ferritin levels were elevated because of increased iron stores or because of infection. If infection is present, it might cause both the elevated serum ferritin levels and the neutrophil dysfunction. Several clinical studies have found an association between high serum ferritin levels and increased infectious risk. In studies that control for important covariates such as use of catheters and previous infections, the infectious risk associated with iron administration or elevated serum ferritin levels is reduced or eliminated. Collectively, these studies suggest that our current understanding of the relationship between iron and infection is incomplete and further studies are needed. There is no reason to alter current iron treatment strategies based on this literature.