The aim of the present study was to relate the clinical course in patients after a first acute myocardial infarction with the site and size of infarct, estimated from standard enzyme measurements. One hundred and eight consecutive patients who suffered an acute myocardial infarction for the first time were followed-up after 30 months in general practice. Twenty-six patients had died and 8 had had another infarction. Sixty-two of the surviving patients had received treatment for ischaemic heart disease, usually for angina pectoris and less often for heart failure and arrhythmias. No correlation was found between ischaemic heart disease requiring treatment and the enzyme-estimated size or the site of the infarct. With anterior infarcts there was, however, an overweight of arrhythmias requiring treatment. Of the patients at work, 31% had changed job or job status because of ischaemic heart disease. At the end of the 30 month period, 50 patients were in functional class 1 and 2, and 32 in functional class 3 and 4 (New York Heart Association's classification).