Nine patients with cardiac failure which was refractory to medical treatment, and which was caused by chronic malfunction of the posterior papillary muscle, as a result of a myocardial infarction, were studied by cardiac catheterisation and coronary arteriography. The mean pulmonary capillary pressure was 31+/-16 mm of mercury with a nu wave at 51+/-27 mm of mercury. The end diastolic volume was increased (141+/-68 ml/m2) and the ejection fraction lowered (0.40+/-0.13). The left ventricle had overall hypokinesia in 5 patients and akinesia of the inferior wall, representing 21+/-24% of the end diastolic perimeter, in 3 others. All these patients had significant lesions of two or three of the main coronary trunks. At operation lengthening of the posterior papillary muscle and/or the cordae was found. All patients had a replacement mitral valve of the Starr-Edwards type, associated with an aorto-coronary bypass of the anterior descending artery. The operative mortality was zero. At a mean follow-up period of 21 months, there had been no late death, and all the patients were improved.