Since 1968 special units for registering and following up all myocardial infarction patients have been in operation in Góteborg. The present paper reports on the deaths and non-fatal reinfarctions among 440 men and women below 67 years of age followed for two years after hospitalization for myocardial infarction. Of the 359 men, 299 had their first infarction and 60 a recurrent infarction. During two years 13% of men with a first infarction, and 37% of men with a recurrent infarction died. Deaths were significantly more common during the first than during the second year. There was no significant difference in mortality between men and women. The incidence of non-fatal reinfarctions was of similar magnitude and showed similar time relationships. Two thirds of the deaths were sudden (within 24 hours after onset of new symptoms) and half of the deaths occurred outside hospital. The autopsy rate was 92%. Two thirds of the deaths were caused by a fresh morphological infarct. In one fourth of the deaths where no cause was found at autopsy, death was ascribed to malignant arrhythmias. Heart weights were higher among patients dying after recurrent infarction at entry to the study. No distinctive pattern was found when autopsy findings were correlated to the interval between the onset of symptoms and death. Deaths due to fresh infarction and without an identifiable cause were more common among those who died within 24 hours of onset of symptoms compared to those dying after longer intervals.