Eighteen consecutive patients satisfying predefined clinical criteria for embolic strokes were prospectively studied by sequential computerized tomography (CT). Their findings were compared to CT scans obtained from patients presumed to have suffered thrombotic strokes. Our data reveal that the CT appearance of hemorrhagic infarction is likely to occur twice as frequently (22%) in CT scans of strokes presumed embolic than in those presumed thrombotic, where hemorrhagic infarction appeared at some time in 10% of the patients. No patient deteriorated with anticoagulation regardless of the CT appearance. In patients showing hemorrhagic infarction before anticoagulants, follow-up scans obtained after the administration of anticoagulants revealed resolution of the hemorrhagic aspect.