Behçet's disease is a chronic, relapsing, inflammatory process with clinical features of aphthous oral and genital ulcerations, uveitis, cutaneous vasculitis, arthritis, and central nervous system involvement. Large-vessel vasculitis, thrombophlebitis, and gastro-intestinal ulcerations may occur. As in other rheumatologic diseases, a genetic predisposition coupled with a triggering event leads to alterations in immune function and response, with variable clinical disease manifestations. Mononuclear cell activation and cytokine release, neutrophil chemotaxis, and humoral immune response with elevations of circulating immune complexes contribute to the pathogenesis of Behçet's disease. Vasculitis and vascular involvement are highlighted. There is no single diagnostic test for Behçet's disease. Treatment is comprised of anti-inflammatory and immunosuppressive agents and, in selected individuals, anticoagulation. Isolated central nervous system vasculitis or noninfectious primary (granulomatous) angiitis of the central nervous system is reviewed briefly. This condition is rare, predominantly affects young women, and includes symptoms of headache, weakness, and confusion. Characteristically, erythrocyte sedimentation rate is normal, serologic studies are negative, and cerebral angiography shows multifocal and segmental vascular narrowing and beading. Typical histopathology is granulomatous in less than 50% of patients, followed by necrotizing or lymphocytic vasculitis, or both, often with thrombosis. Treatment with immunosuppressive agents improves symptoms and outcome.