It is estimated that one-third of the world's population is anemic, the majority being due to iron deficiency (ID). In adults, ID is associated with fatigue in the absence of anemia, restless legs syndrome, pica and, in neonates, delayed growth and development. In adolescents, ID is associated with decrements in learning and behavioral abnormalities. In the absence of a clear cause, search for a source of bleeding is indicated. No single test is diagnostic of ID unless the serum ferritin is low or the percent transferrin saturation is low with an elevated total iron binding capacity. Oral iron is considered front line therapy except for conditions such as gastric bypass, heavy uterine bleeding, inflammatory bowel disease, and hereditary hemorrhagic telangiectasia. Oral iron has many unpleasant side effects, resulting in low patient adherence. For patients intolerant of, or unresponsive to, oral iron, intravenous (IV) administration is the preferred route. While early formulations were associated with a high incidence of serious adverse events (SAEs), newer formulations are much safer with SAEs occurring very infrequently. Full replacement doses can be administered in a matter of minutes to a few hours. Nevertheless, there remains a reluctance to use IV iron due to a misunderstanding of the safety of the available formulations. IV iron is safe and effective in all clinical circumstances including pregnancy. The preponderance of published evidence suggests IV iron therapy is underutilized and we believe that IV iron should be moved forward in the treatment of ID and iron deficiency anemia (IDA).