Reintervention was required in 123 (12%) individuals during a follow up (mean 7.5 years, range 5-14.5) of 1041 patients with consecutive, isolated, first aortocoronary bypass operations. In 89 patients the intervention was a repeat bypass operation, in 24 it was angioplasty, and 10 had both. Procedure related mortality was significantly higher at reintervention (5.6%) than at the primary operation (1.2%). Survival probability after a single bypass procedure was 90% at six years and 82(3)% at nine years. Corresponding figures six and nine years after reintervention were 89(6)% and 87(7)% respectively. Stepwise multivariate analysis showed that survival was significantly correlated with left ventricular function (rate ratio 1.82) and with extent of vascular disease (rate ratio 1.80) but not with reintervention (rate ratio 1.45). Symptomatic improvement occurred in 89% of the survivors with or without reintervention. Repeat procedures are often necessary after coronary artery bypass grafting but they appear to provide appreciable relief of symptoms without reducing any long term improvement in survival brought about by the original operation.