OBJECTIVE: To assess the quality of reported consent processes of cluster-randomised trials conducted in residential facilities for older people and to explore whether the focus on improving the general conduct and reporting of cluster-randomised trials influenced the quality of conduct and reporting of ethical processes in these trials. DESIGN: Systematic review of cluster-randomised trials reports, published up to the end of 2010. DATA SOURCES: National Library of Medicine (Medline) via PubMed, hand-searches of BMJ, Journal of the American Medical Association, BMC Health Services Research, Age and Ageing and Journal of the American Geriatrics Society, reference search in Web of Knowledge and consultation with experts. ELIGIBILITY FOR SELECTING STUDIES: Published cluster-randomised trials where the unit of randomisation is a part or the whole of a residential facility for older people, without language or year of publication restrictions. RESULTS: We included 73 trials. Authors reported ethical approval in 59, obtaining individual consent in 51, and using proxies for this consent in 37, but the process to assess residents' capacity to consent was clearly reported in only eight. We rated only six trials high for the quality of consent processes. We considered that individual informed consent could have been waived legitimately in 14  of 22 trials not reporting obtaining consent. The proportions reporting ethical approval and quality of consent processes were higher in recent trials. CONCLUSIONS: Recently published international recommendations regarding ethical conduct in cluster-randomised trials are much needed. In relation to consent processes when cognitively impaired individuals are included in these trials, we provide a six-point checklist and recommend the minimum information to be reported. Those who lack capacity in trials with complex designs should be afforded the same care in relation to consent as competent adults in trials with simpler designs.