The echocardiographic appearance of fibrotic thickening and calcification of mitral valve chordae tendineae and left ventricular papillary muscles in 17 patients is described. Pathologic proof of excessive fibrosis or calcification was obtained in five patients. In a sixth patient, calcium was demonstrated on angiography to extend from the chordae into papillary muscle. The characteristic feature of chordal and papillary muscle fibrosis and calcification is the presence of highly echogenic densities best visualized within the left ventricle at a level below the mitral valve leaflets. The more inferior location of these densities, within the body of the left ventricle, enables them to be easily differentiated from densities indicating fibrosis and calcification of the mitral valve anulus. The pattern of chordal and papillary muscle fibrosis and calcification was frequently associated with mitral anular calcification, aortic valve fibrosis or calcification and left atrial enlargement. One patient had rheumatic mitral valve disease. Many patients had mitral regurgitation and most had a history, physical examination and radiologic findings compatible with congestive heart failure. Although the origin and importance of the chordal and papillary muscle changes reported are not known, their frequent association with mitral regurgitation and with congestive heart failure suggests possible interrelations.