Objective To determine whether changes in coronary-care unit therapy for elderly patients with acute myocardial infarction have been associated with improved survival. Material and Methods We conducted a retrospective cohort analysis of all patients 70 years of age or older from Olmsted County, Minnesota, who were hospitalized in a coronary-care unit in this county for the treatment of acute myocardial infarction during one of three periods: 1976 through 1978, 1987 through 1989, and 1991. The effect of aspirin, heparin, β-blockers, thrombolysis, percutaneous transluminal coronary angioplasty, and coronary artery bypass grafting on these elderly patients with acute myocardial infarction was assessed. Results Improvement in 30-day survival was significant for patients 80 years of age or older (45%,69%, and 78% in 1976 through 1978, 1987 through 1989, and 1991, respectively; P = 0.01 for the trend) but not for patients 70 to 79 years of age (77%, 76%, and 81% for the three time periods, respectively; P = 0.65 for the trend). The opposite pattern was observed for survival in the period more than 30 days after the event. More intensive treatment in the hospital was associated with better 30-day survival (P < 0.0001). Conclusion The improved survival of the elderly patients with acute myocardial infarction in these cohorts can be accounted for by changes in the therapy they received in the coronary-care units.