Poor medication adherence or non-adherence to the prescribed medications amongrnMyocardial Infraction patients is a common problem. This leads to hospital admission due tornincreased MI exacerbations, reduced physical function, and even death. Previous researchrnindicated that medication adherence is influenced by several issues, including side effects,rncosts of the medication, dosing frequency and routes of administration. However, research onrnmedication adherence and its associate factors among adult post MI patients in Ethiopia isrnlimited. The objective of this study was to assess Medication adherence and its associatedrnfactor among adult post myocardial infarction patients at Tikur Anbessa Specialized andrnLandmark General Hospitals in Addis Ababa, Ethiopia. An Institutional based cross-sectionalrnstudy was conducted between February 2021 March 2021. Two hospitals with cardiac centersrnwere selected by lottery method. And proportional Samples were allocated to each hospital.rnSample size was calculated using single population proportional formula and the calculatedrnsample size for this study was 422. Data was analyzed using SPSS version 25. Descriptivernstatistics was used to summarize socio- demographic, characteristics of study participants.rnMedication adherence was measured by adherence scale interviewer-administeredrnquestionnaire. Logistic regression was used to identify factors associated with outcomernvariables. The result was reported by odds ratio (OR) and Statistical significance was declaredrnat p-value less than 0.05. A total of 401 study participants were recruited with a response raternof 95 %. Adherence rate for MI medication was 57.1%. Age (AOR=4.565; 95% CI (2.3348.933)),rnincomern(AOR=1.693rn95%rnCIrn(1.018-2.816),rnsexrn(AOR=1.863rn95%rnCIrn(1.045-3.322),rnrnhavingrnrnno complex (AOR= 1.906 95 % CI (1.157-3.141)), and side effect of drug (AORrn=3.858 95% CI (2.282-6.523)) were positively associated with medication adherence. cost ofrnmedication (92.3%) followed by availability of medications (83.8%) were the main reasonsrnfor medication non - adherence. Slightly more than half of the respondents are adherent torntheir medication but majority of the respondents worried about the availability of medications.rnSo, it is recommended that the government should ensure the availability of medications.