A national epidemiological study undertaken in November 1995 recensed the data of 2563 patients admitted to 373 Intensive Care Units for acute myocardial infarction. There were 1827 men and 736 women with an average age of 67 years. Seventeen per cent of patients had left ventricular ejection fration (LVEF) < or = 35%. The mortality rate at 5 days was 7.7%. Clinical heart failure (Killip > 1) was observed in 34.4% of patients. 63% of patients were admitted before the 6th hour. Forty-six per cent of patients underwent early revascularisation by thrombolysis and/or angioplasty. The most widely used drugs in the first 5 days were heparin (96%), aspirin (89%), betablockers (65%), and angiotension converting enzyme inhibitors (46%). The influence of region on the demographical features, morbidity, mortality and therapeutic practice was studied. France was divided into 6 regions. In the Centre, the patients were older, with increased morbidity and mortality compared with the national average. Patients in the North East were similar and had a higher incidence of obesity. In the Ile de France, patients were generally younger with a higher incidence of tobacco consumption and their infarcts were generally less severe. Finally, in the South East, the mortality was particularly low. In multivariate analysis living in this region was good prognostic factor whereas low LVEF (< or = 35%) and age > or = 65 years were poor prognostic factors. This study, for the first time in France, describes the clinical features of myocardial infarction admitted to the Intensive Care Unit with respect to criteria of severity (LVEF, Killip) and region of origin of the patients. Its confirms large regional variations in the severity of acute myocardial infarction.