Cross-sectional echocardiography identified two abnormal patterns of mitral valve closure in 14 patients with mitral regurgitation due to papillary muscle dysfunction: (1) in three patients with an akinetic inferior-posterior wall but normal cavity size, papillary muscle fibrosis was associated with late systolic mitral valve prolapse, and (2) in nine patients with ventricular dilatation or ventricular aneurysm, the point of mitral valve coaptation was displaced towards the apex of the left ventricle. In two of these patients both abnormalities were observed. In contrast, abnormal patterns were identified in only four of a group of 40 patients without angiographic evidence of mitral regurgitation (10, normal; 27, coronary artery disease; three, congestive cardiomyopathy). Thus, cross-sectional echocardiography can be useful to identify mitral regurgitation secondary to papillary muscle dysfunction.