Although thrombosis of St. Jude valve prosthesis is rare, we report a case of multiple thromboembolism in a patient who had stopped anticoagulant therapy. The consequences were very severe since two abdominal operations (colonic resection) were necessary. Since the patient was not compliant with anticoagulant therapy, aortic valve replacement was performed and a biologic valve implanted. The postoperative phase was long but the patient left the hospital after two months' treatment. This case again demonstrates the importance of anticoagulant therapy in patients with a prosthetic heart valve. Addition of dipyridamole diminished the risk of thromboembolic accident and should be added to the anticoagulant regimen.