ABSTRACT rnBackground: Heart failure is a progressive and complex clinical syndrome that can occur duernto impairment of cardiac structure or function that leads to the inability of the heart to fill withrnor pump sufficient amount of blood to meet the metabolic need of the body. Medicationrnadherence is crucial to controlling symptoms, delaying disease progression, and preventingrnhospitalization in heart failure. However, poor medication adherence is associated withrnincreased re-hospitalization, morbidity, mortality and increased health care cost. rnObjective: This study aims to assess medication adherence and associated factors among adultrnheart failure patients at selected public health teaching hospitals in Addis Ababa, Ethiopia. rnMethods: A hospital based cross-sectional study among adult heart failure patients wasrnconducted at cardiac follow up clinic of Tikuranbessa specialized hospital, St. Paulâ€™srnmillennium medical college, Armed force specialized Hospital and Yekatit 12 Hospital fromrnMarch 8-April 21,2021. A total of 385 patients were included and a systematic simple randomrnsampling technique was used to select patients. Data collection was done through patientrninterview using pre tested structured questionnaire. The data was coded, edited, and entered inrnto Epi data version 4.4 then exported to SPSS version 25 for analysis. Variables having a p-rnvalue,0.25 in the bivariate analysis was a candidate for multivariable analysis. Variables havingrna p-value < 0.05 in the multivariable analysis were assumed as statistically significant factors. rnResults: A total of 385 participants were included with a response rate of 100%. More thanrnhalf (67.8%) of the participants were females and the mean age was 46.27Â±16. Of the studyrnparticipants (48.6%) adhered to medication. Education about medication AOR (95% CI)rn=2.127 (1.038,4.357), educational level AOR (95% CI) =6.044 (1.952,18.708) were positivelyrnassociated with medication, fewer HF symptom AOR (95% CI) =0.044 (0.006,0.304), patientrnforgetfulness AOR (95% CI) =0.064 (0.034,0.121), cost of the drugs AOR (95% CI=0.413rn(0.208,0.820) were negatively associated with medication adherence. rnConclusion and recommendation: This study assessed the prevalence of medicationrnadherence. The factors that affect medication adherence were education about medication,rneducation level, fewer heart failure symptom, cost of medication and patient forgetfulness.rnhealth professionals should give education about medication to improve treatment adherence.