Large left atrial mural thrombi in the absence of mitral valve stenosis have been reported rarely in the literature. It is even rarer without history of atrial fibrillation (AF). These masses can cause systemic embolization and sudden circulatory collapse when they obstruct the mitral valve. We are presenting a case of giant, free floating ball thrombus, detected after aortic valve replacement for mixed aortic valve disease. It was found immediately before separation from cardiopulmonary bypass by transoesophageal echocardiography and was successfully removed. A ball thrombus without mitral valve disease and AF with aortic valve disease is not yet reported in the literature.