Ferumoxytol is a new product approved for intravenous use by the US Food and Drug Administration (FDA) in the treatment of iron deficiency anemia in adults with chronic kidney disease. This approval was based on data from 3 open-label, randomized, controlled clinical trials. In all of these trials, ferumoxytol was well tolerated, and hemoglobin levels were significantly increased compared with those achieved by orally administered iron. Ferumoxytol, a superparamagnetic iron oxide coated with a carbohydrate shell, is also used as a magnetic resonance imaging (MRI) agent due to its magnetic properties. In addition, it has demonstrated a greater T1 relaxation time than MRI gadolinium-contrast agents. Currently, the Ferumoxytol Compared to Iron Sucrose Trial (FIRST) has started. This is a multicenter randomized trial of ferumoxytol compared with iron sucrose for the treatment of iron deficiency anemia in adult subjects with chronic kidney disease, where intravenous ferumoxytol is being compared with other intravenous agents to evaluate the safety of ferumoxytol and assess changes in hemoglobin level.