Uveitis is a clinical feature of the Blau syndrome, a disease linked to CARD15 (also referred to as NOD2) mutations. Three main mutations in this gene (R334W, R334Q and L469F) have been reported as Blau syndrome risk factors, a disease that manifests uveitis as one of its clinical features. However, little is known on the involvement of this gene in idiopathic uveitis. We thus sought to determine the frequency of these Blau-related CARD15 mutations in a cohort of Spanish patients with idiopathic uveitis. To this aim, 110 patients with idiopathic uveitis, followed at the Department of Ophtalmology of a tertiary hospital (Hospital Universitario Alcalá de Henares, Madrid. Spain) were enrolled. As a control population, 104 healthy subjects were used. DNA was extracted from blood samples and the Blau-related CARD15 mutations were analysed either by PCR-RFLP or direct DNA sequencing. None of the mutations studied was found in any of the individuals tested, whether diseased or healthy. It seems thus that Blau syndrome-related CARD15 mutations are not involved in idiopathic uveitis, a finding which allows us to suggest that the genetic aetiology of the idiopathic uveitis or the Blau-associated uveitis is different.