This section reviews the history, pharmacology, administration, efficacy, and toxicity of intravenous iron. Intravenous iron offers advantages over oral iron for the treatment of iron deficiency anemia across a wide range of disease states associated with absolute and functional iron deficiency. However, there remain concerns about the acute safety profiles of the available preparations and the potential for long-term toxicity with their repeated administration. Seven intravenous iron formulations are available. Confusion concerning the relative toxicities of the different formulations abounds. The similarities and differences are discussed. Iron repletion has been associated with adverse outcomes in infections. The relationship, if any, between intravenous iron administration and infections is reviewed. The potential advantages of total dose infusion (TDI), complete repletion in a single setting, are highlighted. A new paradigm for iron replacement therapy in iron deficiency anemia is presented.