IntroductionThe growing number of smartphone health applications available in the app stores makes these apps a promising tool to help reduce the global problem of non-adherence to long-term medications. However, to date, there is limited evidence that available medication reminder apps are effective. This study aims to determine the impact of medication reminder apps on adherence to cardiovascular medication when compared with usual care for people with coronary heart disease (CHD) and to determine whether an advanced app compared with a basic app is associated with higher adherence.Methods and analysisRandomised controlled trial with follow-up at 3 months to evaluate the feasibility and effectiveness of medication reminder apps on medication adherence compared with usual care. An estimated sample size of 156 patients with CHD will be randomised to one of three groups (usual care group, basic medication reminder app group and advanced medication reminder app group). The usual care group will receive standard care for CHD with no access to a medication reminder app. The basic medication reminder app group will have access to a medication reminder app with a basic feature of providing simple daily reminders with no interactivity. The advanced medication reminder app group will have access to a medication reminder app with additional interactive and customisable features. The primary outcome is medication adherence measured by the eight-item Morisky Medication Adherence Scale at 3 months. Secondary outcomes include clinical measurements of blood pressure and cholesterol levels, and medication knowledge. A process evaluation will also be performed to assess the feasibility of the intervention by evaluating the acceptability, utility and engagement with the apps.Ethics and disseminationEthical approval has been obtained from the Western Sydney Local Health Network Human Research Ethics Committee (AU/RED/HREC/1/WMEAD/3). Study findings will be disseminated via usual scientific forums.Trial registration numberACTRN12616000661471; Pre-results