Anemia is a common feature of chronic renal dysfunction and is associated with significant morbidity and mortality. Although acquired insufficiency of erythropoietin is virtually universal, iron deficiency is also a common contributor to the development of anemia. Iron replacement, in particular via the intravenous route, has become commonplace and results in improved hematocrits either on its own or in association with an erythropoiesis stimulating agent. However, intravenous iron is not without its potential complications. These include acute allergic reactions, iron overload, potentially accelerated cardiovascular disease and risk of infection. It is the purpose of this review to critically evaluate the available clinical and experimental evidence linking iron supplementation therapy with these complications.