Darbepoetin alpha (DA) is a unique long-acting treatment for anaemia in patients with chronic renal failure (CRF). This study assessed the mean dose of DA to achieve and maintain haemoglobin (Hb) levels between 11 g/dl and 13 g/dl in CRF children aged 11 years to 18 years. This observational, prospective study was conducted in 39 patients treated with DA. Twenty-nine patients were switched from recombinant human erythropoietin (r-HuEPO), and ten patients were naive to r-HuEPO. Naive patients received initial doses of 0.45 microg/kg of DA. Switched patients received a dose adjusted to the prior dose of r-HuEPO (200 IU r-HuEPO:1 microg DA). Among the switched patients, 79.3% received dialysis. No naive patients underwent dialysis. Overall, 74% of patients showed increased Hb level, with a mean value of 11.6 +/- 1.6 g/dl, using a mean DA dose of 0.63 +/- 0.48 microg/kg per week, and 66.7% patients reached the target Hb level. Hb increased in naive patients from 9.5 (95% CI: 7.7, 11.4) to 11.7 (95% CI: 10.9, 12.6) g/dl and in switched patients from 11.1 (95% CI: 10.6, 11.5) to 11.5 (95% CI: 10.8, 12.2) g/dl). Higher doses of DA were needed in the "switched" than in the "naive" patients to maintain Hb levels over 11 g/dl, respectively 0.73 (95% CI: 0.54, 0.92) and 0.34 (95% CI: 0.16, 0.52) microg/kg per week. Our results indicate the doses of DA necessary to treat CRF patients aged 11 years to 18 years. DA was an effective treatment to stabilise CRF patients at extended dosing intervals.