Background: Patients undergoing maintenance dialysis for kidney failure are at substantial risk of cardiovascular morbidity and mortality. We aimed to establish if spironolactone reduces heart failure and cardiovascular deaths in these patients. Methods: ACHIEVE was an international, parallel-group, randomised controlled trial done in 143 dialysis programmes in 12 countries. Patients were aged 45 years or older, or aged 18 years or older with a history of diabetes, and were receiving maintenance dialysis for kidney failure for at least 3 months at the time of recruitment. Patients who were able to tolerate and adhere to spironolactone 25 mg daily orally during an open-label run-in were randomly assigned (1:1) to continue spironolactone or matching placebo, using a central computerised block randomisation system (block sizes of 4) stratified by centre. Participants, health-care providers, and those assessing outcomes were masked to group assignment. The primary outcome was a composite of cardiovascular mortality or hospitalisation for heart failure analysed as time-to-event in all randomly assigned participants. The trial was registered at ClinicalTrials.gov, NCT03020303. Findings: After a planned interim analysis of 75% of the expected primary outcome events, the external safety and efficacy monitoring committee recommended the trial be stopped early for futility. From Sept 19, 2017, to Oct 31, 2024, 3689 patients were screened for inclusion, 3565 of whom were enrolled in the open-label run-in phase, and 2538 were randomly assigned to spironolactone (n=1260) or placebo (n=1278). 931 (36·7%) participants were female and 1607 (63·3%) were male. Median follow-up was 1·8 years (IQR 0·85–3·35). The composite primary outcome occurred in 258 participants (10·46 events per 100 patient-years) in the spironolactone group and in 276 participants (11·33 per 100 patient-years) in the placebo group (hazard ratio [HR] 0·92 [95% CI 0·78–1·09]; p=0·35). Death from any cause was similar between groups (HR 0·95 [0·83–1·09]) as was hospitalisation for any cause (HR 0·96 [0·87–1·06]). Interpretation: Among patients receiving maintenance dialysis, spironolactone 25 mg daily orally did not reduce the composite outcome of cardiovascular mortality and hospitalisation due to heart failure compared with placebo. This trial did not identify a benefit of initiating spironolactone in patients receiving maintenance dialysis. Future research should consider alternatives to steroidal mineralocorticoid receptor antagonism to reduce cardiovascular morbidity and mortality in patients receiving maintenance haemodialysis. Funding: The Canadian Institutes of Health Research, The Medical Research Future Fund, The Health Research Council, The British Heart Foundation, Population Health Research Institute/Hamilton Health Sciences Research Institute, St Joseph's Healthcare Hamilton Division of Nephrology, Accelerating Clinical Trials Consortium, Can-SOLVE CKD Network, and the Dalhousie Department of Medicine.