ABSTRACT Background: Atrial fibrillation is supra ventricular arrhythmia with uncoordinated atrial activation and, consequently, ineffective atrial contraction. Atrial fibrillation is one of the complications of rheumatic heart disease, with substantial morbidity and mortality. It is a growing public health problem, with enormous human, economic, and social burdens. Studies regarding the prevalence and factors associated with atrial fibrillation among chronic rheumatic heart disease in Ethiopia are scarce. Therefore, this study will assess the prevalence and factors associated with atrial fibrillation in patients with chronic rheumatic heart disease. Objective: To determine the prevalence and factors associated with atrial fibrillation among patients with chronic rheumatic heart disease attending public referral Hospitals in Bahir Dar city, North West Ethiopia,2023. Methods and Materials: A hospital based cross sectional study was conducted from October/2023- November/2023. Data were collected with chart review by using the pre-developed data collection checklist. A total of 410 participants were included. A systematic random sampling method was used. Data were entered to Epi data version 4.6 and then exported to SPSS 26 version software for analysis. Binary logistic regression model was used to identify variables significantly associated with outcome variable. Variables with a 95% CI and p-value ≤ 0.25 during bi-variable logistic regression were entered in to multivariable analysis. In the final multivariable regression model, factors will be considered significantly associated if p value is less than 0.05. Data were presented in word and tables. Results: In this study, 410 charts were reviewed. Prevalence of atrial fibrillation was 43% with 95% CI of 38% up to 48%. Being males (AOR = 3.81, 95% CI 2.00-7.26), age (> 30 years) (AOR = 7.26, 95% CI 3.93-13.41), Patients who had heart failure (AOR = 4.65, 95% CI 2.39-9.04), mitral valve stenosis (AOR = 6.36, 95% CI 2.92-13.87) and left atrial diameter enlargement (AOR = 3.41, 95% CI 1.64-7.09) were more likely to develop atrial fibrillation. Conclusions and recommendations: Prevalence of atrial fibrillation was 43%. Sex, age, heart failure, mitral valve stenosis and left atrial diameter enlargement were associated with atrial fibrillation. The health care professionals better to give special attention and clinical care as accordingly for patients with associated factors of atrial fibrillation