Despite the initial overall good results of aorto-coronary bypass grafting for myocardial revascularisation, a small but increasing number of patients require consideration for reoperation after the first procedure. In the period 1973 to 1981, 36 reoperations were performed in 34 patients with one operative death. In all of them the clinical indication for reoperation was recurrence of angina pectoris. In this special group of patients a high incidence of risk factors was present. Three major probable causes for the recurrence of angina were found: (1) Progression of the coronary atherosclerotic disease; (2) Graft failure; (3) Incomplete original revascularisation. Combined factors were present in 18 (53%) patients. There were no statistically significant differences in the incidence of postoperative complications at the first and second operation. Follow-up of 79% of the 33 survivors over a mean time period of 18 months, demonstrated no late mortality and a low subsequent infarction rate. Overall 69% of patients either lost their angina or were improved. We therefore conclude that reoperation can be accomplished with low mortality and morbidity and has a potential therapeutic benefit in the majority of cases.