During a 21-month period, the prognosis in all patients admitted to a hospital ward from the emergency room with suspected acute myocardial infarction (AMI) was prospectively recorded and related to the time between onset of symptoms and arrival in hospital. They were classified as early arrivers (≤ 2 h), intermediate arrivers (2–8 h) and late arrivers ( > 8 h). Among patients developing a confirmed AMI (n = 909) the 1-year mortality rate was 26.0% in early arrivers, 28.1% in intermediate arrivers and 32.6% in late arrivers. The corresponding figures for patients in whom AMI was ruled out (n = 2,035) were 15.2, 15.1 and 17.6%, respectively. In AMI patients, various morbidity aspects during hospitalization and 1 year of follow-up appeared mainly independent of delay time, whereas among those in whom AMI was ruled out congestive heart failure during hospitalization was most common in early arrivers. We conclude that patients with suspected AMI who do not arrive early in hospital have a high 1-year mortality rate regardless of whether they develop AMI or not. Whether their prognosis can be improved by shortening of delay time remains to be clarified.