Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disease of the vascular connective tissue. Pulmonary arteriovenous and cerebral vascular malformations are risk factors for serious neurological complications such as paradoxical embolism and intracranial hematomas. We describe two patients with HHT and pulmonary arteriovenous malformations suffering from stroke caused by paradoxical embolism. In both cases, fistulas were successfully treated by embolisation and no further cerebral ischemic events occurred. In ischemic strokes of unknown origin, HHT should be considered as a possible diagnosis with effective treatment options.