BACKGROUND: The mortality of cardiovascular disease has decreased substantially in later years though it is uncertain whether this decrease is due to a better profile of risk factors in the population or to improvements in medical treatment. MATERIAL AND METHODS: In 1982 to 1984 and 1997 to 1999 all patients admitted to Hedmark Central Hospital in Norway, with acute myocardial infarction were registered and followed for reinfarction and survival over up to three years. A total of 1,236 patients were included in the study, 641 in the first time period and 595 in the second. RESULTS: A significant decrease in case fatality was observed in the second population. The seven days fatality rate decreased from 17.9% to 11.4%, and the one month fatality rate from 22.9% to 16.1%. The median number of days in hospital decreased from ten to six. A Kaplan-Meier estimate for survival in the total follow-up period showed a 43% higher relative death risk in the 1982-1984 cohort compared to the 1997-1999 cohort. A Cox regression revealed that this difference could not be explained by demographic differences between the populations. INTERPRETATION: By evaluating variables registered during the course of infarction in the multivariate Cox model, it is concluded that improved survival in the recent cohort is related to modern treatment of acute myocardial infarction.