As part of an ongoing community-wide study of time trends in the incidence and case-fatality rates of patients hospitalized with acute myocardial infarction (MI) in 16 Worcester, Mass., metropolitan hospitals during the calendar years 1975, 1978, 1981, and 1984, changes over time in the therapeutic management of 3,263 patients with validated acute MI were examined. Beta-blocker and nitrate therapy use increased consistently and dramatically. Use of antiplatelet agents was inconsistent, while use of digoxin remained stable. Use of antiarrhythmic medications other than lidocaine decreased consistently while lidocaine use increased between 1975 and 1978 and then leveled off to being used in approximately 45% of hospitalized patients with acute MI in 1981 and 1984. A variety of demographic (e.g. age, sex, teaching hospital) and clinical characteristics (e.g. MI order, MI type, MI location, peak CPK findings, occurrence of acute clinical complications) were also associated with the use of these therapies. The results of this community-wide study suggest changes over time in the therapeutic management of patients hospitalized with acute MI and of various patient demographic and clinical factors associated with the use of these agents.