OBJECTIVES: The main aim of this retrospective study was to perform a cost-minimization analysis of long term use of Darbepoetin-á (DARB) after switch from erythropoietin beta (EPO-â)in treating chronic nephropathy-induced anemia in dialysed patients. METHODS: We extracted data of 78 patients who have been treated with EPO-â for at least 6 months and then switched to DARB from the database of the dialysis center of the Asti (Piedmont, Italy) hospital. From these, we selected 47 patients (23 males and 24 females) who completed a 120-weeks follow-up treatment with DARB. All patients were treated with a dose adjustment schedule to keep hemoglobin levels in the range 11-12g/dl. Pre-switch EPO-â administration was thrice a week, while DARB was administered once a week, both via intravenous. Initial DARB dose has been calculated on the basis of the theoretical 200:1 conversion factor. Drug costs were valued according to current (October 2006) purchasing prices for the Italian National Health System. RESULTS: The average actual conversion factor from EPO-â to DARB at the end of 120 weeks of follow-up resulted 280:1. The initial DARB dose, chosen on the basis of the recommended conversion factor, induced an excessive erythropoietic response, which was generally followed by a gradual dose reduction. In the 24 pre-switch weeks the average cost (±SD) per patient for EPO-â was 2309.86 (1434.78) Euro. In the 120 weeks of follow-up the average cost (±SD) per patient for DARB/24 weeks ranged from a minimum of 1487.09 (1125.51) Euro to a maximum of 2125.73 (1546.85) Euro. The switch of 47 patients to DARB produced an overall net saving for the dialysis center estimated in 119,540.72 Euro/120 weeks. CONCLUSION: The conversion from EPO-â to DARB has the potential to maintain good haemoglobin control also in the long term and induces significant savings for the National Health System.