The aim of our research was to study the long-term prognosis among patients discharged alive after an out-of-hospital cardiac arrest (OHCA) in comparison with patients discharged alive after acute myocardial infarction (AMI) without OHCA, and also to study the long-term influence of AMI in connection with OHCA. Our research was conducted in the municipality of Göteborg. We retrospectively studied patients discharged from hospital 1990-91 after an OHCA of cardiac aetiology and patients discharged after an AMI without prehospital cardiac arrest. During 1980-98, we studied all patients discharged alive after OHCA of cardiac aetiology, divided into groups of precipitating AMI and no AMI. The study includes 48 patients discharged alive after an OHCA 1990-91, 30 (62%) of whom had a simultaneous AMI and 1425 patients with an AMI without OHCA. Compared with AMI survivors, survivors of an OHCA of cardiac origin were younger but had more frequently a history of congestive heart failure. Their mortality rate during the subsequent 5 years was 46%, compared with 40% among survivors of an AMI (NS). The 5-year mortality rate among patients with an OHCA precipitated by an AMI was 40%. When correcting for differences at baseline, the adjusted risk ratio for death among patients with an OHCA of cardiac origin was 1.2 (95% CI 0.8-1.8) compared with patients with an uncomplicated AMI. During 1980-98, 215 patients were judged as having an OHCA precipitated by an AMI and 115 patients had an OHCA of cardiac aetiology but no simultaneous AMI. Five-year mortality was 54% and 50% respectively (NS). It is concluded that survivors of an OHCA of cardiac origin differed from survivors of an uncomplicated AMI in that they were younger and more frequently had a history of cardiovascular disease. Their 5-year mortality after discharge was similar to that of survivors of an AMI without a prehospital cardiac arrest, even after adjusting for differences at baseline.