Warfarin can be taken routinely after mitral valve replacement surgery. The duration of warfarin varies depending on the type of valve being replaced. 1. Biologic valves: If the valve replaced is a biologic valve and no atrial fibrillation occurs after surgery, patients usually need to take warfarin for 6 months. If the valve replaced is a biologic valve and atrial fibrillation occurs after surgery, patients may need to take warfarin for anticoagulant therapy for the rest of their lives. 2. Mechanical valves: Patients with mechanical valves will require lifelong anticoagulation with warfarin. Warfarin is indicated for patients who require long-term continuous anticoagulation for the treatment of thromboembolic diseases, prevention of thrombosis, and as an adjunct to myocardial infarction. Common adverse reactions include bleeding, allergy, and nausea and vomiting. Warfarin is contraindicated in patients with severe hepatic or renal impairment, severe hypertension, coagulopathy with bleeding tendency, recent surgery or trauma. Patients undergoing mitral valve replacement surgery are advised to undergo regular review and take medication as prescribed by the doctor.