We evaluated the prognosis of 599 diabetics who came to the emergency department with chest pain or other symptoms suggestive of acute myocardial infarction (AMI). They made up 8% of the patients with such symptoms (n = 7,157). Diabetics had a 1-year mortality rate of 25% as compared with 10% for nondiabetics (p less than 0.001). The difference remained significant regardless of whether there was a strong or a vague initial suspicion of AMI. On admission, independent risk factors for death were age, acute congestive heart failure and initial degree of suspicion of AMI. We conclude that among diabetics who appear in the emergency department with chest pain or other symptoms suggestive of AMI, 25% are dead within 1 year. The prognosis is directly related to the initial suspicion of AMI.