Ruptured papillary muscle due to myocardial infarction was encountered in 14 patients during the period 1975-1983. Five of the 14 patients had a history of angina pectoris and two had a history of prior myocardial infarction. Eleven patients with myocardial infarction developed additional pain due to myocardial ischemia and/or a murmur of mitral regurgitation and pulmonary edema within a week, 3 others had a prolonged course with intermittent pain due to myocardial ischemia and breathlessness for longer periods and then deteriorated. Thirteen of our 14 patients developed a murmur and all but one had pulmonary edema on the chest x-ray. Five patients had infarction patterns on the electrocardiogram, the remainder of the patients had only ST- and T-wave changes. Echocardiograms showed fine flutter and notching of the anterior mitral leaflets and vigorous contractions of the left ventricle. Only one patient was demonstrated to have a papillary muscle tip prolapsing into the left atrium on two-dimensional echocardiography. Twelve patients underwent surgery and 8 survived. Seven patients had single-vessel coronary disease, 4 involving the circumflex system and 3 involving the right coronary system. Four of the 7 patients with single-vessel coronary disease survived surgery. Five patients went to surgery with the intra-aortic balloon pump in place and only 3 survived. Three others had the pump inserted intraoperatively and 2 of these survived. Six of 9 patients who had mitral valve replacement and coronary bypass survived. Ejection fraction ranged from 40 to 79%. Surgical survival did seem to be related to the extent of papillary muscle rupture, with the best results occurring in the group with a small portion of the tip ruptured. Seven patients had a stormy clinical course and required surgery within 10 days of rupture. Four of these 7 survived. It seems reasonable to believe that these patients who often have small infarction and limited coronary disease have good potential for survival. Our approach has been to move toward surgery once the diagnosis is made to avoid the sudden deterioration that frequently occurs. The surgical mortality in this group remains in the 30 to 40% range.