Iron deficiency anemia is common among hospitalized patients, and blood losses from diagnostic phlebotomy increase the likelihood of a negative iron balance. The role for iron supplementation of total parenteral nutrition (TPN) in these patients is unclear. Twenty-three patients with iron deficiency anemia were identified. Twelve patients were randomized to receive TPN without iron (group 1) and 11 received TPN supplemented with 10 mg of iron as iron dextran daily (group 2). Both groups were matched for age, serum iron studies, red cell indices, and hemogram. After a 7-d period, the mean serum iron in group 2 increased from 10 to 26 micrograms/dL, with an increased transferrin saturation from 7.3 to 15.3% (each, p < 0.05). No changes in total iron binding capacity, ferritin, reticulocyte count, hemoglobin, hematocrit, or mean corpuscular volume were observed in the two groups. The incidence of infectious complications was not different between both groups. We conclude that iron supplementation of TPN appears safe and is effective in increasing serum iron levels. The use of iron-supplemented short-term TPN needs to be further studied given no change in red cell indices, hemoglobin, hematocrit, or transfusion requirement.