Studies that used short message service (SMS) programs as an intervention to promote health care have shown beneficial results in the control of risk factors for ischemic heart disease in patients of high-income countries, but evidence is lacking in low or middle-income countries. The purpose of this study is to evaluate whether the use of SMS increases risk factor control within 6 months after discharge by acute coronary syndrome (ACS) in a middle-income country. It will be a 2-arm, parallel, double-blind, randomized clinical trial of 160 patients discharged after an ACS from a single center with 6 months of follow-up. The intervention group will receive 4 SMS per week offering advice, motivation and information about medication adherence, increase of regular physical activity, adoption of healthy dietary measures, and smoking cessation (if appropriate). The primary outcome is achieving 4 or 5 points in a risk factor control score, which combines the cluster effect of 5 main modifiable risk factors for ACS low-density lipoprotein cholesterol, LDL-C <70 mg/dL, blood pressure <140/90 mm Hg, regular exercise (≥5 days/week × 30 minutes of moderate exercise per session), nonsmoker status, and body mass index, BMI <25 kg/m. Secondary outcomes are plasma LDL-C level, level of physical activity, blood pressure, medication adherence, proportion of nonsmokers, BMI, rehospitalization, cardiovascular death, and death from any cause. This study, as a randomized clinical trial protocol, followed the recommendations of the Standard Protocol Items (SPIRIT). This study aims to provide evidence of whether SMS interventions are effective in improving cardiovascular disease risk factors control in post-ACS patients in a middle-income country. CLINICALTRIALS. NCT03414190 (First posted on January 29, 2018; last update on May 14, 2018) - Retrospectively registered.