Aims: The aim of this study was to investigate the effects of spironolactone on left ventricular (LV) remodeling in patients with preserved LV function following acute myocardial infarction (AMI). Methods and Results: Successfully revascularized patients (n = 186) with acute ST elevation MI (STEMI) were included in the study. Patients were randomly divided into three groups, each of which was administered a different dose of spironolactone (12.5, 25 mg, or none). Echocardiography was performed within the first 3 days and at 6 months after MI. Echocardiography control was performed on 160 patients at a 6-month follow-up. The median left ventricular ejection fraction (LVEF) increased significantly in all groups, but no significant difference was observed between groups (P = 0.13). At the end of the sixth month, the myocardial performance index (MPI) had improved in each of the three groups, but no significant difference was found between groups (F = 2.00, P = 0.15). The mean LV peak systolic velocities (Sm) increased only in the control group during the follow-up period, but there is no significant difference between groups (F = 1.79, P = 0.18). The left ventricular end-systolic volume index (LVESVI) and the left ventricular end-diastolic volume index (LVEDVI) did not change significantly compared with the basal values between groups (F = 0.05, P = 0.81 and F = 1.03, P = 0.31, respectively). Conclusion: In conclusion, spironolactone dosages of up to 25 mg do not augment optimal medical treatment for LV remodeling in patients with preserved cardiac functions after AMI. © 2012 John Wiley & Sons Ltd.