To assess whether the manifestations of acute ischemic heart disease in the elderly are less typical than in younger patients, the presenting clinical features and their associated relative risks for acute myocardial infarction (AMI) were compared in 2,625 patients greater than or equal to 65 years of age and 5,109 patients less than 65 years of age. These patients were evaluated for acute chest pain in the emergency departments of 7 hospitals. The same features were associated with increased relative risks for AMI in younger and elderly patients. The relative risks among older patients, however, were consistently closer to 1.0 for classic features, including male gender, pressure-like quality of pain, substernal location, typical pattern of pain radiation and electrocardiographic evidence of ischemia or AMI. Analyses for the endpoint "acute ischemic heart disease" (i.e., AMI or unstable angina) yielded similar findings. Elderly patients were more likely to be admitted to the hospital (56 vs 35%; p less than 0.0001) and to the coronary care unit (37 vs 23%; p less than 0.0001) in the absence of either AMI or unstable angina. These data support the hypothesis that diagnosis of acute chest pain is especially difficult in elderly patients.