Background and aim: The studies on effects of amiodarone and diltiazem, on conversion of atrial fibrillation (AF) to normal sinus rhythm (NSR) in patients of rheumatic heart disease (RHD) with AF undergoing valve replacement surgery are very less. In this study, we compared the effect of amiodarone and diltiazem on conversion of AF to NSR. Methods: Seventy five patients of RHD with chronic AF undergoing valve replacement surgery were randomly assigned into three groups(each contained 25 patients). In group C normal saline was given. In group A, injection amiodarone 3mg/kg, IV given over 10 minute before skin incision followed by continuous infusion at 0.3mg/kg/h till the end of surgery. In group D injection diltiazem 0.25mg/kg, IV over 10 minute followed by continuous infusion at 0.1mg/kg/h till the end of surgery. Results: The percentage of patients converted to NSR at aortic declamping was not significantly different in amiodarone and diltiazem group: 80% in amiodarone and 92% in diltiazem group. The conversion to NSR in control group was 28% and the difference was significant when compared to amiodarone (p=0.00) and diltiazem (p=0.00) group. The patients required DC shock in diltiazem group (4%) were significantly less as compare to amiodarone (28%, p=0.02) and control (44%, p=0.00) group. Conclusion: Amiodarone and diltiazem both are equally effective and safe to convert AF to SR. Diltiazem is better than amiodarone to reduce the requirement of defibrillation.