Background: Erythropoiesis-stimulating agents are used to treat anaemia in people with chronic kidney disease (CKD). Several agents are available including epoetin alfa or beta as well as agents with a longer duration of action, darbepoetin alfa and methoxy polyethylene glycol-epoetin beta. Objectives: To assess the benefits and harms of darbepoetin alfa to treat anaemia in adults and children with CKD (stages 3 to 5, 5D, and kidney transplant recipients). Search methods: We searched the Cochrane Renal Group's Specialised Register (to 13 January 2014) through contact with the Trials' Search Co-ordinator using search terms relevant to this review. Studies contained in the Specialised Register are identified through search strategies specifically designed for CENTRAL, MEDLINE and EMBASE. Selection criteria: We included randomised controlled trials of any darbepoetin alfa treatment of at least three months duration in adults or children with CKD (any stage). Data collection and analysis: Data were extracted by two independent investigators. Patient-centred outcomes (need for blood transfusion, iron therapy, progression of kidney disease, total and cardiovascular mortality, cardiovascular events, cancer, hypertension, seizures, and health-related quality of life) and other outcomes (haemoglobin levels) were assessed using random effects meta-analysis. We calculated risk ratios for dichotomous outcomes and mean differences for continuous outcomes, both with 95% confidence intervals. Main results: We identified 32 studies comprising 9414 participants; 21 studies in 8328 participants could be included in our meta-analyses. One study (4038 participants) compared darbepoetin alfa to placebo, 16 studies (2955 participants) compared darbepoetin alfa to epoetin alfa or beta, four studies (1198 participants) compared darbepoetin alfa to methoxy polyethylene glycol-epoetin beta, three studies (420 participants) compared more frequent with less frequent darbepoetin alfa administration and four studies (303 participants) compared intravenous with subcutaneous darbepoetin alfa administration. In a single large study, darbepoetin alfa reduced the need for blood transfusion and iron therapy compared with placebo in adults with CKD stage 3 to 5, but had little or no effect on survival, increased risks of hypertension, and had uncertain effects on quality of life. Data comparing darbepoetin alfa with epoetin alfa or beta or methoxy polyethylene glycol-epoetin beta were sparse and inconclusive. Comparisons of differing dosing schedules and routes of administration were compared in small numbers of participants and studies. Evidence for treatment effects of darbepoetin alfa were particularly limited for children with CKD, adults with CKD stage 5D, and recipients of a kidney transplant. Studies included in this review were generally at high or unclear risk of bias for all items (random sequence generation, allocation concealment, incomplete outcome data, blinding of participants and personnel, blinding of outcome assessment, selective outcome reporting, intention to treat analysis and other sources of bias). One large study comparing darbepoetin alfa with placebo was at low risk of bias for most items assessed. Authors' conclusions: Data suggest that darbepoetin alfa effectively reduces need for blood transfusions in adults with CKD stage 3 to 5, but has little or no effect on mortality or quality of life. The effects of darbepoetin alfa in adults with CKD stage 5D and kidney transplant recipients and children with CKD remain uncertain as do the relative benefits and harms of darbepoetin alfa compared with other ESAs (epoetin alfa or beta and methoxy polyethylene glycol-epoetin beta).