BACKGROUND Falls and fall-related fractures are highly prevalent among older people and are a major contributor to morbidity and costs to individuals and society. Only one small pilot trial has evaluated the effectiveness of a home hazard assessment and environmental modification in the UK. This trial reported a reduction in falls as a secondary outcome, and no economic evaluation was undertaken. Therefore, the results need to be confirmed and a cost-effectiveness analysis needs to be undertaken. OBJECTIVE To determine the clinical effectiveness and cost-effectiveness of a home hazard assessment and environmental modification delivered by occupational therapists for preventing falls among community-dwelling people aged ≥ 65 years who are at risk of falling, relative to usual care. DESIGN This was a pragmatic, multicentre, modified cohort randomised controlled trial with an economic evaluation and a qualitative study. SETTING Eight NHS trusts in primary and secondary care in England. PARTICIPANTS In total, 1331 participants were randomised (intervention group, n = 430; usual-care group, n = 901) via a secure, remote service. Blinding was not possible. INTERVENTIONS All participants received a falls prevention leaflet and routine care from their general practitioner. The intervention group were additionally offered one home environmental assessment and modifications recommended or provided to identify and manage personal fall-related hazards, delivered by an occupational therapist. MAIN OUTCOME MEASURES The primary outcome was the number of falls per participant during the 12 months from randomisation. The secondary outcomes were the proportion of fallers and multiple fallers, time to fall, fear of falling, fracture rate, health-related quality of life and cost-effectiveness. RESULTS The primary analysis included all 1331 randomised participants and indicated weak evidence of a difference in fall rate between the two groups, with an increase in the intervention group relative to usual care (adjusted incidence rate ratio 1.17, 95% confidence interval 0.99 to 1.38; p = 0.07). A similar proportion of participants in the intervention group (57.0%) and the usual-care group (56.2%) reported at least one fall over 12 months. There were no differences in any of the secondary outcomes. The base-case cost-effectiveness analysis from an NHS and Personal Social Services perspective found that, on average per participant, the intervention was associated with additional costs (£18.78, 95% confidence interval £16.33 to £21.24), but was less effective (mean quality-adjusted life-year loss -0.0042, 95% confidence interval -0.0041 to -0.0043). Sensitivity analyses demonstrated uncertainty in these findings. No serious, related adverse events were reported. The intervention was largely delivered as intended, but recommendations were followed to a varying degree. LIMITATIONS Outcome data were self-reported by participants, which may have led to inaccuracies in the reported falls data. CONCLUSIONS We found no evidence that an occupational therapist-delivered home assessment and modification reduced falls in this population of community-dwelling participants aged ≥ 65 years deemed at risk of falling. The intervention was more expensive and less effective than usual care, and therefore it does not provide a cost-effective alternative to usual care. FUTURE WORK An evaluation of falls prevention advice in a higher-risk population, perhaps those previously hospitalised for a fall, or given by other professional staff could be justified. TRIAL REGISTRATION Current Controlled Trials ISRCTN22202133. FUNDING This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 25, No. 46. See the NIHR Journals Library website for further project information.