Behçet's disease is a multisystem disease featuring mucocutaneous, ocular, intestinal, articular, vascular, urogenital, and neurologic involvement. While classically intermittent in its manifestations, the disease can stabilize and become chronic in a given organ system. The diagnosis of Behçet's disease is based on clinical criteria. Recurrent aphthous ulcerations in the mouth, skin lesions, eye lesions, and genital ulcerations must be present during the course of the disease for a diagnosis of Behçet's disease to be made unequivocally. A nonspecific skin hyperreactivity called pathergy is said to be helpful in the diagnosis. There are no pathognomonic laboratory findings, but biopsy usually shows a venulitis. The pathogenesis of the disease is unknown. No virus has been satisfactorily isolated to date. There is evidence of an increased frequency of HLA-B5 and HLA-B12. Humoral and cellular immunity seem to play a major part in the pathogenesis of the various manifestations of the disease. The treatment of Behçet's disease is difficult to evaluate because of the many spontaneous exacerbations and remissions during the clinical course of the disease. Topical corticosteroids for orogenital ulcers and ocular inflammation are helpful. Intralesional injections for affected joints and retrobulbar tissues are useful in some cases. Systemic corticosteroids have appeared to be helpful for all manifestations of the disease. It is customary to use 60 mg of prednisone by mouth daily during acute exacerbations, then to taper as the condition improves. Chlorambucil has been shown to be safe and effective for various manifestations of Behçet's disease; often it is used in combination with corticosteroids.(ABSTRACT TRUNCATED AT 250 WORDS)