Perioperative infarction is a significant factor of morbidity of coronary bypass surgery. The aim of this study was to review peri-operative infarction and its complications over a 10 year period (1974 to 1984) and to determine its consequences on left ventricular function and life expectancy. The material included 514 patients who underwent coronary bypass surgery. Perioperative infarction was defined as the association of a postoperative Q wave and increase in creatinine phosphokinase after the 24th postoperative hour: this diagnosis was made in 31 cases (Group A), 6 per cent of the series; 483 patients (Group B) had no signs of infarction. The necrosis involved the revascularised zone in 26 cases and other zones in 5 cases. The acute phase of infarction was associated with major complications in 9 patients of Group A. In 22 patients (70 per cent of cases) the initial evolution was uncomplicated. There was no significant difference in the number of patients with unstable angina between Groups A and B (52 per cent vs 67 per cent), with single vessel disease (25 per cent vs 28 per cent), double vessel disease (45 per cent vs 34 per cent) or with triple vessel disease (30 per cent vs 38 per cent). The average number of bypasses was higher in Group A (2.06 per cent vs 1.4 per cent, p less than 0.05), as was the duration of cardiopulmonary bypass (117 min vs 91 min, p less than 0.05) and of aortic clamping (45 min vs 31 min, p. less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)