Administration of oral ferrous salts is the preferred method of treatment for anemia due to iron deficiency. However, in certain clinical situations, the response to oral therapy may be suboptimal. Parenteral iron therapy is effective in these instances and may produce a faster response than the oral route.Of 30 patients treated by total dose intravenous infusion of iron-dextran, a prompt reticulocytosis occurred in all patients except one case associated with systemic lupus erythematosus. Hematologic improvement in this case followed remission of the systemic lupus erythematosus. Hematologic response was complete in 18 patients in five to nine weeks, but could not be evaluated in 11 cases because of recurrent bleeding. There were two adverse reactions: generalized pruritus after injection in one patient, and superficial thrombophlebitis at the injection site of another.The response to therapy in iron deficient anemia is dependent on bone marrow capacity, the severity of the anemia, and the availability of iron. Response was fastest in those who had been severely anemic for prolonged periods of time. Total dose infusion with iron-dextran is a safe and effective treatment for iron deficient anemia in selected cases. Initial response appears to be faster than that on oral therapy with the exception of those with a mild degree of anemia.