The 1-year prognosis of 293 patients discharged alive from the hospital after acute myocardial infarction (AMI), who experienced primary ventricular fibrillation (VF) in the acute phase, was compared with that of a reference group of 6,337 patients identified from the same population included in the Gruppo Italiano per lo Studio della Streptochinasi nell'Infarto miocardico (GISSI) trial. There was no difference in the 6- and 12-month mortality between the patients with primary VF and the reference group (3.7 vs 2.7% and 4.1 vs 4.2%, respectively). Survival of the 2 groups was also similar when patients were stratified according to infarct site (anterior and posterior), and whether or not they received treatment with streptokinase during AMI. Thus, long-term mortality of patients discharged alive after AMI complicated by primary VF is low and is not influenced by previous fibrinolytic therapy or by infarct site. The excess mortality of patients with primary VF is confined to the hospital phase, after which survivors represent a low-risk subgroup.