The Swiss cantons of Vaud and Fribourg participate in the international MONICA project (MONI-toring of trends and determinants in CArdiovascular disease). Within this context, drug therapies and procedures were recorded during two separate years (1986 and 1990) for all hospitalizations of men aged 25 to 64 with the diagnosis of myocardial infarction. The medical files were reviewed to classify this diagnosis as possible or definite on the basis of the symptoms, the ECG results and the enzymatic tests. The two study populations (n = 318 in 1986 and n = 332 in 1990) are comparable with respect to age, history of ischemic heart disease and initial care. In 1990, half of the patients arrived at hospital in less than 3 hours, the median time delay being 4 hours for those first attending a general practitioner and 2 hours for those transferred directly. The frequency of treatments between 1986 and 1990 is compared only for cases with a definite diagnosis of myocardial infarction (respectively n = 217 and n = 223). The proportion of patients given thrombolytic therapy rose from 9% to 44% (p < 0.005) and from 51% to 95% (p < 0.005) for those treated with antiplatelet drugs, whereas the proportion fell from 72% to 55% (p < 0.005) for calcium blockers and from 33% to 24% (p < 0.05) for inotropic drugs. The use of anticoagulants (in 98% of patients) and of beta blockers (in 57%) remained stable across time.(ABSTRACT TRUNCATED AT 250 WORDS)