The results of a consecutive series of 24 patients reoperated for coronary bypass grafting between May 1977 and February 1983 are reported. The overall incidence of reoperation was 1.4 p. 100 (24 out of 1 716 cases); the incidence is tending to increase (2.3 p. 100 in 1982). Preoperative assessment revealed the persistence of cardiovascular risk factors: 75 p. 100 of patients had continued to smoke; 61 p. 100 had persistent hyperlipidaemia. The usual presenting syndrome was recurrence of chest pain (21 out of 24 cases) leading to control coronary arteriography on the results of which the surgical indication was based. The average time between the two operations was 38.7 months. The patients were classified into two groups; early reoperation (6 cases) for a technical problem or incomplete revascularisation, and late reoperation (8 cases) for disease of the graft and atherosclerosis. Progression of coronary atherosclerosis was the major long-term cause of occlusion of the saphenous graft (10-14 cases). The arteries most commonly bypassed at reoperation were the left anterior descending and right coronary arteries (12 times each). Reoperation comprised single bypass (13 cases), double bypass (10 cases) and triple bypass (1 case) with an average of 1.5 grafts per patient. The most commonly used vein was the internal saphenous vein (32 out of 36 grafts). Myocardial protection was insured by cardioplegia (13 cases) and intermittent clamping (10 cases) after cooling (general hypothermia at 22 degrees C). Global reoperative mortality (4 p. 100) was higher than for elective primary coronary surgery (2.3 p. 100). The incidence of perioperative infarction was 8 p. 100.(ABSTRACT TRUNCATED AT 250 WORDS)