Objectives: There is recent evidence that aldosterone play a role in the pathogenesis of cardiovascular disease in dialysis patients, which leads to the opportunity to block its actions for the benefit of these patients. In nondialytic chronic kidney disease, spironolactone was safe and effective in reducing left ventricular hypertrophy. However, routine use has been precluded in hemodialysis patients due to the risk of hyperkalemia. The aim of this study is to verify the safety and efficacy in regression of left ventricular hypertrophy with spironolactone in hemodialysis patients undergoing pharmacotherapeutic monitoring. Methods: We performed a controlled, randomized, double blind study evaluating 17 hemodialysis patients who received spironolactone at a dose of 12.5 mg titrated, in the second week, to 25 mg of spironolactone or placebo. The patients were treated for 6 months. Results: The groups were composed of eight patients (intervention) and nine patients (control). These groups did not differ in their baseline characteristics. The group receiving spironolactone had a left ventricular mass index reduction from 77 ± 14.6 g/m^2.7 to 69 ± 10.5 g/m^2.7, p < 0.04, whereas in placebo group there was an increase from 71 ± 14.2 g/m^2.7 to 74 ± 17.4 g/m^2.7. Systolic or diastolic blood pressure did not change during the study. Potassium did not differ statistically between groups in all instances. Conclusion: Spironolactone treatment in hemodialysis patients was secure and effective in regression of left ventricular hypertrophy, a major risk factor for cardiovascular events in these patients. This effect occurred in spite of blood pressure stability. Trial registration: ClinicalTrials.gov identifier NCT01128101