AIM: To evaluate whether long-term treatment with a fixed low dose of warfarin in combination with aspirin improves the prognosis compared with aspirin treatment alone after an acute myocardial infarction (AMI). METHODS: Patients who were hospitalized for AMI were randomized to either 1.25mg of warfarin plus 75mg of aspirin (n=1659) daily or 75mg of aspirin alone (n=1641). The study was performed according to the PROBE (Prospective Open Treatment and Blinded End Point Evaluation) design and was conducted at 31 hospitals in Sweden. The median follow-up time was 5.0 years. In the aspirin+warfarin group, 30.2% were permanently withdrawn as opposed to 14.0% in the aspirin group (P