Age is one of the important prognostic factors for acute myocardial infarction. This study was performed to clarify the clinical characteristics and outcome of acute myocardial infarction in Chinese geriatric patients. The study subjects included 742 patients, divided by age into 2 groups: Group A greater than or equal to 65 years, 321 cases; and Group B less than 65 years, 421 cases. The following characteristics were compared between these 2 groups: sex composition; presence of chest pain, heart failure or shock at presentation; cardiac functional status; occurrence of various complications, and follow-up data. Males were less prominent in the older group: 229 patients (71.3%) in Group A, and 371 patients (88.1%) in Group B. At onset, the older patients presented with less chest pain (72% vs 86.5%) and more heart failure (35.2% vs 20.2%), but the occurrence of shock was similar (5.9% vs 4.5%, for Groups A and B, respectively). During hospitalization, more patients in Group A showed impaired cardiac function, as evidenced by a higher percentage of patients identified as in Killip class III or IV (35.4% vs 21.1%). Concerning complications, the older group showed a higher incidence of hypotension, low cardiac output, lung edema, frequent premature ventricular beats, atrial flutter and/or fibrillation, complete heart block and intraventricular conduction defects, but ventricular septal defects, ventricular tachycardia and ventricular fibrillation did not show any difference in occurrence. Life table analysis showed that the survival rate was significantly lower for Group A during the follow-up period of 5 years.(ABSTRACT TRUNCATED AT 250 WORDS)