Factor V Leiden is already well established to be involved in venous thrombosis but not in coronary heart disease. Results are conflicting and even antagonistic in cerebrovascular disease (CVD). In this study we examine the prevalence of factor V Leiden in 125 consecutive patients with ischemic CVD 12 additional selected CVD patients with the first CVD episode before the age of 45 years, and 102 controls from the same area. Identification of the mutation was achieved using two molecular methods. The prevalence of factor V Leiden in patients with CVD was similar to that in the normal population. The presence of the mutation was independent of the age and severity of the ischemic episode. Finally, no significant clinical differences were found between patients with and those without factor V Leiden. Therefore, factor V Leiden cannot be considered as a genetic risk factor for CVD.