Two hundred and forty one patients with iron deficiency anemia (IDA) were identified in a single institution over a 24-year period; of these, 75 individuals were studied as the result of persistent IDA despite the administration of oral iron hydroxide polymatose (IP). The levels of hemoglobin when the patients were referred for study after being given oral IP had a median of 10.3 g/dl; after administration of oral iron fumarate during periods ranging from 1 to 14 months, the levels of hemoglobin rose to a median of 12.5 g/dl (p>0.01). Our data support previous observations made in other countries about the ineffectiveness of oral IP in the treatment of individuals with IDA and should alert the clinician to avoid unnecessary consultations and misdiagnosis.