Background: Parenteral iron therapy is required in a majority of chronic dialysis patients who are receiving recombinant human erythropoietin (r-HuEPO) in order to provide adequate iron for erythropoiesis. At this time, there are only two formulations of parenteral iron dextran available for clinical use in the USA. These two preparations of iron dextran have different physical and chemical characteristics that might affect the adverse events experienced by dialysis patients receiving iron dextran. Methods: We performed a retrospective analysis of all 665 courses of parenteral iron dextran which were administered in our hemodialysis unit from June 1992 through July 1997. An adverse event (AE) was defined as any event which led to interruption of the prescribed course of iron therapy or precluded subsequent administration of parenteral iron in the presence of documented iron deficiency. Database elements included patient age, gender, cause of renal failure, and prior history of drug allergy. The average hemoglobin value and serum iron parameters (iron, total iron binding capacity (TIBC), percent saturation of TIBC, and ferritin) were recorded both pre- and post-iron administration, when available. A course of parenteral iron dextran consisted of a 25-mg test dose, followed by four or five doses of 300 mg each. Iron dextran was infused into the venous limb of the hemodialysis blood circuit over the last 30–60 min of a dialysis treatment. The two forms of iron dextran were designated as Iron A (molecular weight = 165,000) and Iron B (molecular weight = 267,000). Results: Fifty-seven percent of our patients were male, 92% were of white race, and diabetes was the most common cause of renal failure (34%). Sixty-four percent of the patients were 60 years of age or older, and 39% had a history of allergy to one or more drugs. We observed 33 AEs during the administration of parenteral iron dextran, and these AEs occurred in 21 courses of parenteral iron dextran administration. Eighteen of the AEs were gastrointestinal in nature; 7 AEs were cutaneous in nature, 6 AEs had systemic manifestations, while only 2 AEs caused respiratory problems. Two of the AEs were felt to be anaphylactoid in nature. Female gender (p = 0.06) and iron dextran product (p = 0.02) were identified as potential risk factors for the development of an AE. There were 468 courses of Iron A administered, 10 of these courses were complicated by 15 AEs (one or more AE per course). One hundred and ninety-seven courses of Iron B were administered and 11 (5.6%) courses were complicated by the development of 18 AEs (9.1 AEs per 100 courses). Serum iron rose by 22 µg/dl and TIBC saturation increased by 14% after the administration of parenteral iron. The average serum ferritin level rose by 430 µg/l and hemoglobin values rose by an average of 0.8 g/dl. There were no significant differences in the changes of iron parameters or hemoglobin levels between the two iron dextran preparations. Conclusions: The administration of parenteral iron dextran to chronic hemodialysis patients has a relatively high degree of safety. Both iron products were equally efficacious in increasing serum iron parameters and hemoglobin levels. Even when corrected for other factors, there was a significant difference in the observed AEs between the two formulations of parenteral iron dextran. Our observations, if true, may have important implications for the management of anemia in chronic hemodialysis patients. If a significant number of AEs prohibit the administration of a specific iron dextran product to a large number of chronic hemodialysis patients, then anemia management may become suboptimal. In the future, newer iron products may provide even safer alternatives for the administration of parenteral iron to chronic hemodialysis patients.