A case of a 61 year old male with lateral myocardial infarction, congestive heart failure and fever of days is presented. The exact etiology of this patient's heart failure was established with the application of transesophageal echocardiography. The transthoracic two-dimensional and Doppler echo showed a mobile echogenic density attached to the tip of the anterior mitral leaflet accompanied by moderate mitral regurgitation. Transesophageal echocardiography attributed this echogenic density to a ruptured head of the anterolateral papillary muscle, resulting in severe mitral regurgitation. Cardiac catheterization confirmed the severe mitral regurgitation and uncovered significant stenotic lesions of the coronary arteries. The resultant surgical treatment for the replacement of the mitral valve and coronary artery by-pass confirmed the rupture of the head of the anterolateral papillary muscle. It is suggested that transesophageal echocardiography is particularly capable of providing a definitive and prompt diagnosis of papillary muscle rupture.