Background and Objectives: One of the important factors in the persistence of cardiovascular diseases and their complications is non-adherence to the treatment regimen. This study was conducted to compare the effects of two methods of education and follow-up by telephone and virtual messenger on adherence to the treatment regimen of patients with acute coronary syndrome. Materials & Methods: In this semi-experimental study, which was conducted in 2025 in hospitals under the supervision of Abadan University of Medical Sciences, 102 patients with acute coronary syndrome hospitalized in the CCU ward were selected using purposive sampling with inclusion and exclusion criteria and were divided into three groups by simple random sampling: the first intervention group (education and follow-up by telephone, 34 people), the second intervention group (education and follow-up via WhatsApp, 34 people), and the control group (34 people). The groups were trained for two weeks and followed up for two weeks. The data collection tools in this study were a demographic questionnaire and a treatment regimen adherence questionnaire. The data were analyzed with statistical tests and SPSS version 27 software. Results: The mean age of the groups was 47/66± 7/8 years in the telephone group, 46/32± 5/8years in the WhatsApp group, and 46/90± 7/1 years in the control group, respectively. In the dietary compliance study, the telephone group performed the highest after the intervention (p<0/001). For the physical activity variable, both interventions were effective, but the telephone intervention performed more prominently and resulted in the highest score after the intervention compared to the control group (P=0/013). For the medication adherence variable, the WhatsApp intervention was more effective, and this group performed the best after the intervention compared to the telephone and control groups (P=0/0016). Conclusion: The results showed that both intervention methods are useful, but telephone intervention to improve behaviors related to diet and physical activity, and WhatsApp intervention to promote adherence to the medication regimen, are considered more appropriate options. The pattern of time changes in the variables of activity level and medication regimen for the telephone group also indicates the effectiveness of the intervention in this group.