INTRODUCTION: In 2016, cardiovascular diseases (CVDs) led to 17.9 million deaths worldwide, representing 31% of all global deaths. CVDs are the leading cause of mortality worldwide and significant barriers to achieving the sustainable development goals. Modern medicines have been significant in improving health outcomes. However, non-adherence to medication is one of the reasons behind adverse health-related outcomes among patients suffering from atherosclerotic cardiovascular disease in low- and middle-income countries. PATIENTS AND METHODS: This qualitative study was conducted at two tertiary care hospitals in India and Ghana. A total of 35 in-depth interviews were conducted with atherosclerosis cardiovascular disease (ASCVD) patients. The data were analysed thematically using the Capability Opportunity and Motivation (COM-B) framework. FINDINGS: The findings were summarised under three important broad themes of the COM-B framework: capability, opportunity and behaviour. Under capability, comprehension of disease, medication schedule, and unplanned travel affected adherence among patients. Cost of medication, insurance and access were the critical factors under opportunity, which negatively influenced medication adherence. Mood, beliefs about treatment and outcome expectations under motivation led to non-adherence among patients. Apart from these factors, some important health system factors such as health care experience and trust in the facilities and reliance on alternative medication also affected adherence in both countries. CONCLUSION: This study has highlighted that the health system factors have dominantly influenced adherence to medication in India and Ghana. In India, we found participants to be satisfied with their health care provided at the government hospitals. However, limited time for consultation, lack of well-stocked pharmacy and unclear prescription negatively influenced adherence among participants in India and Ghana. The study emphasises that the health system needs to be strengthened, and the patients' belief system needs to be explored to address the issue of medication adherence in LMICs.