BACKGROUND: Atherosclerotic cardiovascular disease (ASCVD) is a growing public health threat globally, and many individuals remain undiagnosed, untreated, and their condition remains uncontrolled. The key to effective ASCVD management is adherence to pharmacotherapy, and non-adherence has been associated with an increased risk of cardiovascular events and complications such as stroke, further impacting a patient's ability to be adherent. Our qualitative study aimed to explore factors influencing medication adherence in the primary and secondary prevention of ASCVD in Singapore. We propose a synthesized framework, which expands on current understandings of the factors of medication adherence, as a frame of analysis in this study. METHODS: We conducted in-depth, semi-structured interviews with 20 patients over the age of 40 with ASCVD and/or its risk factors in Singapore. QSR Nvivo 11 was used to conduct thematic analysis using an inductive approach. RESULTS: Using a synthesized framework, we reported that complex medication regimens, the lack of support received during regimen changes, and the perceived seriousness of a condition could impact a patient's medication adherence. Key findings suggest that the relationship between health care professionals and patients impacted patient acceptability of the medication regimen and consequently medication adherence. Different patient beliefs regarding diagnosis, medication, and adherence had some bearing on the ability to perceive the need to adhere to their medication. Patients also reported that they could afford medication, sometimes with the help of family members. Patients also largely reported not needing help managing their medication, considering it an individual responsibility. CONCLUSION: We identified key factors which future interventions looking to improve medication adherence ought to consider. These include changing patient perceptions of health systems, diagnosis, medication, and adherence; patient-centeredness in developing interventions that facilitate adherence through building self-efficacy and stronger support networks via patient empowerment and engagement; decreasing patient co-payments on medication; and cultivating a trusting patient-provider relationship.