Behçet's disease is a complex multisystem disease diagnosed by means of clinical criteria. Clinical features include oral and genital aphthae, pustular vasculitic cutaneous lesions, and ocular, gastrointestinal, and vascular manifestations. We believe that complex aphthosis, characterized by oral or oral and genital ulcers, may be a forme fruste of Behçet's disease. Although the pathogenesis of both Behçet's disease and complex aphthosis remain unknown, immune factors, infectious agents, and effector mechanisms are implicated. Treatment is based on the severity of systemic involvement and includes topical therapies as well as colchicine, dapsone, thalidomide, and immunosuppressive agents.