This study documents mortality from acute myocardial infarction (AMI), in hospital and at 1 year, for each of 3 selected 1-year periods in a stable community over a 13-year period beginning in 1979 and continuing into the thrombolytic era, to detect any changes occurring in conjunction with the introduction of new therapies. Every patient with AMI occurring in a geographically defined stable community (Hamilton, Ontario, Canada) in 3 1-year periods (1979 to 1980 [n = 816], 1986 to 1987 [n = 816], and 1991 to 1992 [n = 831]) was identified and clinically characterized by standardized criteria. Subsequent in-hospital and 1-year survival were ascertained prospectively. The 3 cohorts were similar in prognostic factors. Mean age was progressively greater over the study period from 63 years in 1979 to 1980, to 67 years in 1991 to 1992 (p = 0.02). There was no change in in-hospital mortality rates from 1979 to 1980 (17%) and 1986 to 1987 (16%). However, from 1986 to 1987 and 1991 to 1992, in-hospital mortality decreased from 16% to 9% (p < 0.001) and 1-year mortality decreased from 26% to 19% (p < 0.001). For patients who survived the hospital phase of AMI, 1-year mortality did not change and was between 11% and 12% in each of the 3 study periods. From 1986 to 1987 and 1991 to 1992, there was an increase in the use of thrombolytic therapy from 5% to 44% of patients. The acute use of aspirin increased from 30% to 88% and the acute use of beta blockers increased from 19% to 48% of patients. The observed increase in use of these agents could account for half of the actual mortality reduction observed. This prospective population-based survey demonstrates improved in-hospital survival after AMI associated with increased use of established effective therapies between 1987 and 1992. The 1-year mortality of hospital survivors of AMI was unchanged throughout the period of study, remaining at 11% to 12%.