As part of a community-wide study examining time trends in the incidence and case-fatality rates (CFR) of patients hospitalized with acute myocardial infarction (MI) in sixteen hospitals in the Worcester, Massachusetts metropolitan area, the association of age to the incidence rates of initial acute MI and to in-hospital and long-term survival among 2115 patients with validated acute MI was examined. After selected age-specific changes in the incidence rates of initial events of acute MI between 1975 and 1981, the incidence rates of acute MI markedly declined between 1981 and 1984, resulting in decreases in the age-specific incidence rates of initial acute MI between 1975 and 1984. For the combined study periods, the in-hospital CFR of acute MI increased from 5.0% in patients less than 55 years of age to 7.9% in those 55 to 64 years, to 16.1% in those 65 to 74 years and to 32.1% in patients 75 years of age and older. Among discharged hospital survivors, increasing age was related to poorer long-term survival over a 5-year follow-up period. The results of this population-based study reinforce the need for, and importance of, modification of coronary risk factors in both young and older individuals, and of focused therapeutic efforts to salvage jeopardized myocardium in elderly patients hospitalized with acute MI.