To assess trends in attack rate, mortality and case-fatality of acute myocardial infarction (AMI) in Sweden. All 303 324 Swedes discharged from hospitals, or deceased, with a diagnosis of AMI between 1987 and 1995. Analysis based on the National AMI Register in Sweden. The National AMI Register was assembled by linking the records of the National Hospital Discharge Register and the National Cause of Death Register in Sweden. Age-standardized attack rate, mortality and case fatality rates for AMI. Between 1987 and 1995, the age-standardized attack rate of AMI declined by 11% for men and 10% for women, whilst mortality from AMI decreased by 14% for both sexes. The decrease was most pronounced for men below the age of 64, with a reduction of 22% in attack rate and nearly 30% in mortality. There was no change over time in the case fatality rates on the date of attack, including also deaths outside hospital, whilst case fatality within 28 days decreased from 49 to 45% amongst men, and 45 to 42% amongst women. This reduction persisted over 1 year of follow-up. The decrease in attack rate of AMI in Sweden may be attributed both to changes in risk factors amongst the population and to improved medical intervention. The decline in case fatality rates indicates that improved treatment of patients with AMI has contributed to the reduction in mortality. However, the high, and essentially unchanged, proportion of deaths outside hospital stresses the importance of disease prevention.