Auto-antibodies to endothelial calls are found in a variety of vasculitic disorders including two diseases associated with retinal vasculitis: Behcet's disease and multiple sclerosis. In this study we have examined the prevalence of anti-endothelial cell antibodies [AECA] in 15 patients with retinal vasculitis [RV]associated with Behcet's disease, multiple sclerosis or sarcoidosis and 20 patients with idiopathic retinal vasculitis. 47% of patients with RV associated with systemic disease and 35% of patients with idiopathic RV had AECA, compared to 1% of 70 normal controls. The mean levels of AKCA were similar in both groups of patients, and comparable to levels found in other systemic vasculitides.