The value of routine transesophageal echocardiography (TEE) was confirmed by the detection of rare and potentially serious complications in four of 136 patients (2.9%) undergoing valvular surgery. In case 1, one leaflet of a St. Jude Medical (SJM) valve implanted in the mitral position was stuck in the closed position; normal valve function was restored by 90 degrees rotation of the prosthesis. In case 2, moderate regurgitation was observed after mitral valve replacement with a Carpentier-Edwards pericardial bioprosthesis. The mitral valve was replaced with a SJM valve; regurgitation was proved due to a suture loop jamming. In case 3, perivalvular leakage was detected after aortic valve replacement for infective endocarditis; an additional suture stopped the leakage. In case 4, a foreign body was observed in the left atrium after aortic valve replacement for calcified aortic stenosis. The left atrium was re-opened, and a free-floating portion of the calcified native aortic valve was identified and removed. Routine intraoperative TEE in valve surgery permits the identification and management of potentially serious complications before discontinuing cardiopulmonary bypass.