Cardiac rehabilitation programs (CRP) are a set of interventions to improve the prognosis of cardiovascular disease by influencing patients' physical, mental, and social conditions. However, there are no studies evaluating the optimal duration of these programs. We aimed to compare the results of a standard vs a brief intensive CRP in patients after ST-segment elevation and non-ST-segment elevation acute coronary syndrome through the Más por Menos study (More Intensive Cardiac Rehabilitation Programs in Less Time). In this prospective, randomized, open, evaluator-blind for end-point, and multicenter trial (PROBE design), patients were randomly allocated to either standard 8-week CRP or intensive 2-week CRP with booster sessions. A final visit was performed 12 months later, after completion of the program. We assessed adherence to the Mediterranean diet, psychological status, smoking, drug therapy, functional capacity, quality of life, cardiometabolic and anthropometric parameters, cardiovascular events, and all-cause mortality during follow-up. A total of 497 patients (mean age, 57.8±10.0 years; 87.3% men) were finally assessed (intensive: n=262; standard: n=235). Baseline characteristics were similar between the 2 groups. At 12 months, the results of treadmill ergometry improved by ≥ 1 MET in ≥ 93% of the patients. In addition, adherence to the Mediterranean diet and quality of life were significantly improved by CRP, with no significant differences between the groups. The occurrence of cardiovascular events was similar in the 2 groups. Intensive CRP could be as effective as standard CRP in achieving adherence to recommended secondary prevention measures after acute coronary syndrome and could be an alternative for some patients and centers. Registered at ClinicalTrials.gov (Identifier: NCT02619422). Copyright © 2020 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.