Rheumatic heart disease (RHD) is a significant public health problem and Non-adherence to treatment is an important and often unrecognized risk factor for cardiovascular mortality. The study aimed to assess self-reported medication adherence by 8-item Morisky Medication Adherence Scale (MMAS-8) among rheumatic heart disease patients and determine the associated factors. A cross-sectional study was carried out by applying a structured interview to Rheumatic heart disease patients aged 18 or higher in a tertiary hospital in Bangladesh. Among Rheumatic heart disease patients, 63.5% showed medium adherence, 36.5% showed low adherence to medication. Walking habit (P= 0.000), exercise habit (P=0.000), smoking habit (P=0.000), and duration of RHD (P=0.005) found significantly associated with medication adherence. Multiple logistic regression analysis also revealed, don't have walking habit more than 10 minutes at a time (AOR=2.416, 95% CI: 1.212-4.816), don't having exercise habit (AOR=2.420, 95% CI: 1.206 – 4.859), don't having habit of smoking (AOR=0.392, 95% CI: 0.183 – 0.841), duration of RHD for less than 15 (AOR=4.190, 95% CI: 0.851 – 20.631) are independent predictors of adherence. Our study demonstrated medium to low medication adherence in the Morisky Medication Adherence Scale among rheumatic heart disease patients.