Primary mitral valve tumors are rare. We describe the transesophageal appearances of a papillary fibroelastoma (Lambl's giant excrescence) of the anterior mitral valve leaflet causing partial mitral valve obstruction. Transesophageal echocardiography proved particularly useful in identifying the limited attachment of the tumor to the anterior mitral valve leaflet and excluding its attachment to the interatrial septum. These features helped to exclude the possibility of the tumor being a left atrial myxoma, the primary differential diagnosis of the lesion. Transesophageal echocardiography enabled the planned surgical option to be mitral valve repair and also allowed intraoperative monitoring to assess the results of the surgical repair.