Eight randomised clinical trials of angiotensin converting enzyme (ACE) inhibitors versus placebo in myocardial infarction have been published in three years, including over 100,000 patients. High risk myocardial infarction carries a poor prognosis with a 25% death rate at 42 months in SAVE, 23% at 15 months in AIRE and 42% at 37 months in TRACE. This form of myocardial infarction benefits the most from treatment with ACE inhibitors: the relative reductions in risk for the previously mentioned trials were 19%, 27% and 22% respectively, and the absolute reductions in risk of death were 4% at 42 months, 6% at 15 months and 8% at 37 months, respectively. Studies including all forms of myocardial infarction involve populations at lower risk. The effects of ACE inhibitors on mortality are then less obvious: from 7.7% to 7.2% at 5 weeks in ISIS-4, from 7.1% to 6.3% at 6 weeks in GISSI-3, from 9.6% to 9.0% at 4 weeks in CCS-1, corresponding to relative reductions in the risk of death of 7%, 12% and 3% respectively and absolute reductions of the risk of death of 0.5% at 5 weeks, 0.8% at 6 weeks and 0.6% at 4 weeks, respectively. Who should be treated? All patients for 4 to 6 weeks or only high risk patients. When should treatment be started? Some investigators institute treatment from the first day but others think it prudent to wait until the second day. For how long? Four to 6 weeks would be sufficient to counteract ventricular remodelling while the benefits are sustained in the long term. But treatment should be continued long term in high risk patients. Which molecule, which dose and how many times, should it be taken per day? The logical answer is molecules with proven efficacy at the dose given in the clinical trials respecting the number of times indicated per day.