Thirty nine patients, mainly males (84.6%) with an average age of 66 years underwent mitral valve replacement for postinfarction mitral regurtation between March 1971 and December 1987. Twenty four were in Class IV of the NYHA Classification, 9 in Class III and 6 in Class II. All had a history of myocardial infarction predominantly of the inferior wall. The 33 preoperative coronary angiogrammes showed 13 patients with triple vessel disease, 15 with double vessel disease and 5 with single vessel disease. At operation, 13 patients had ruptured papillary muscles; acute dysfunction was observed in 16 and chronic in 10 patients. The hospital mortality was 36%; over three quarters of deaths were due to myocardial dysfunction. Twenty two patients had an associated myocardial revascularisation procedure with mitral valve replacement. All 25 survivors were followed up for an average of 2.3 years (94 patient-years). The 5 year actuarial survival (operative mortality included) was 55% and 77% of the 17 survivors are in Stages I or II of the NYHA Classification. The quality of these long-term results justifies surgery despite the high operative risk.