BACKGROUND: The survival benefit from the use of inhibitors of angiotensin-converting enzyme (ACE) in patients with acute myocardial infarction is usually presented in terms of risk ratios and lives saved per 1000 people treated. A more relevant way to present the extent of benefit would be in terms of an increase in life expectancy, but this approach has not previously been possible because of limited data on long-term outcome. We aimed to calculate the effect of trandolapril on life expectancy with follow-up data from the Trandolapril Cardiac Evaluation (TRACE) Study. METHODS: The TRACE study previously showed a significant survival benefit with trandolapril in patients with reduced left-ventricular function after an acute myocardial infarction who were treated for at least 2 years. We ascertained the survival status of all patients in the TRACE study in June, 1998, at which time they had been followed up for a minimum of 6 years. We estimated life expectancy as median lifetime, which was the time for 50% of the patients to have died. Change in life expectancy is expressed as change in median lifetime. Analysis was by intention to treat. FINDINGS: The life expectancy of patients was 4.6 years for those given placebo versus 6.2 years for those on trandolapril. Thus, for patients on trandolapril, median lifetime was increased by 15.3 months or 27% (95% CI 7 to 51). Analysis of follow-up after the end of the study indicated no decrease of this benefit during the course of double-blind treatment; continued use of trandolapril was recommended at study closure. INTERPRETATION: In patients with severely reduced left-ventricular function, long-term treatment with an ACE inhibitor during the critical period after myocardial infarction is associated with a substantial increase in life expectancy.