Aneurysm of the anterior mitral leaflet is a rare complication of infective aortic valve endocarditis, the natural evolution of which is generally its rupture, with subsequent acute and severe mitral regurgitation. Its presence cannot be recognized with transthoracic echocardiography and even in surgery. We describe a 78-year-old man with aortic valve endocarditis, in whom transesophageal echocardiography was essential for the diagnosis of this complication, its therapeutic management, and the postoperative follow-up after simple valve repair. In addition, the most appropriate surgical approach is discussed.