The aim of this study was to document changes in drug prescription after myocardial infarction. One hundred and seventy four men with typical myocardial infarction recensed by the Toulouse MONICA centre between 1989 and 1990 were followed up for 4.5 years. A copy of their drug prescription was obtained during the acute phase of infarction, at the time of discharge from hospital or clinic, after 6 months, and finally, after 4.5 years after infarction. During the acute phase, the majority of patients received nitrate derivatives, platelet antiaggregants, calcium antagonists, betablockers and antiarrhythmics. Between hospital discharge and the sixth month, the prescription of lipid lowering drugs quadrupled (from 8 to 33%; p < 0.00001) and those of platelet anti-aggregants decreased (from 82 to 70%; p < 0.01). The prescriptions of other drugs remained relatively stable. Between the 6th month and the 4th year of follow-up the only prescription to increase significantly was that of ACE inhibitors (from 14 to 23%; p < 0.03). The other prescriptions were maintained: platelet anti-aggregants (70% at 6 months vs 75% at 4.5 years), nitrate derivatives (59 vs 51%), betablockers (51 vs 52%), calcium antagonists (51 vs 48%), lipid lowering drugs (33 vs 42%), diuretics (3 vs 6%) and inotropic agents (2 vs 2%). Overall analysis showed an increase in the prescriptions of lipid-lowering agents (p < 0.00001) and ACE inhibitors (p < 0.002). On the other hand, the prescriptions of calcium antagonists and nitrate derivatives tended to decrease. These results show that the treatment of patients with coronary artery disease is based on drugs of proven efficacy, reflecting the impact of large scale therapeutic trials on everyday medical practice.