This study reports the results of a point prevalence study of markers of endothelial dysfunction in the serum of patients with idiopathic uveoretinitis. sICAM-1, soluble endothelial leucocyte adhesion molecule (sELAM), anti-endothelial cell antibodies (AECA) and von Willebrand factor (vWF) levels were measured in 32 patients with isolated idiopathic uveoretinitis and seven with uveitis in association with systemic disease, using commercial and in-house ELISAs. Raised levels of AECA were found in 31% of patients with isolated uveitis, vWF in 28%, sELAM in 15.6% and sICAM-1 in 31%. Further analysis revealed that raised sICAM-1 levels were closely associated with recent relapse of disease (P = 0.000 03). Patients with accompanying systemic disease were found to have a similar prevalence of these serum abnormalities to those with isolated ocular disease. In conclusion, vascular endothelial dysfunction may contribute to pathogenesis in uveoretinitis, and in particular sICAM-1 may prove a marker of disease relapse in this condition.