The first 1041 patients who underwent an isolated aorto-coronary bypass operation in the same institution since it opened in 1971, were followed for up to 10 years to determine their prognosis. The mean follow-up time was 3.5 years. The probability of survival at five years was 94 +/- 2% (95% confidence limits). This was similar to the survival of the general Dutch population matched for age and sex. Multivariate survival analysis with the proportional hazards model did reveal a relationship of the rate of death with sex and age at operation; however this was not significant. There was a trend to a higher death rate with more vascular involvement (rate ratio of 3 vessel-versus 1 vessel disease of 1.9, N.S.) and a significant association with a low ejection fraction (EF) (ratio EF less than or equal to 0.30 v. EF greater than or equal to 0.55 of 2.7. P less than 0.05). Though surgery seems to eradicate the poor longterm outlook for patients with more serious vascular disease, the adverse influence of decreased left ventricular function on survival is not changed.