OBJECTIVES: Due to its longer half-life, darbepoetin alfa (DA) is administered at extended dosing intervals compared to epoetin alfa (EPO). The aim of this study was to collect, in routine clinical practice, data about consequences of switching from intravenous (IV) EPO to IV DA in patients (pts) with chronic kidney disease (CKD) receiving dialysis (>12 months). METHODS: This French monocentre observational study included adults with CKD receiving dialysis switched from EPO to DA in July 2010. Data related to EPO and DA dosing and dose frequency, Hb levels, and iron statuses were collected retrospectively over 36 weeks before the conversion and 36 weeks after the conversion. The primary endpoint estimated the dose conversion ratio (DCR) between mean EPO doses (UI) and DA (µg) during 4 weeks pre-conversion and 21-24 weeks post-conversion. The mean DCR was determined with a regression-based method using ordinary least squares (LSQ). RESULTS: A total of 93 pts were enrolled in this study, (61.3 % female, mean age 70.3 years (mean time on dialysis 5.2 years). The primary etiologies of CKD were mainly diabetes (37.6 %) and hypertension (12.9 %). The arithmetic mean (± SD) EPO dose/injection at inclusion was 4193 ± 3417 UI with the following injection frequency: x3/week (44.1 %), x2/week (32.3 %), x1/week (21.5 %) or other (2.1 %). The mean (± SD) DCR on the evaluable population (83 patients, 10 excluded due to missing data) was 271.3 ± 30.4 (95% CI 264.7, 277.9). The mean (± SD) Hb values were equivalent over the pre- and post-conversion periods 11.2 ± 0.9 and 11.1 ± 1.0 g/dL, respectively. Iron status was also similar. CONCLUSIONS: In routine clinical practice, the mean DCR observed in our French dialysis centre, was higher than the factor 200UI:1µg recommended in the DA Summary of Product Characteristics and applied at switch.