Behçet's disease is a complex, multisystem disease that was first described in 1937 by the Turkish dermatologist, Hulusi Behçet, but may have been recognized since ancient times. In his original description, Behçet referred to a symptom complex of recurrent oral aphthous ulcers, genital aphthae, and iritis that could lead to blindness. Additional clinical manifestations include the pathergy phenomenon (the induction of a cutaneous pustular neutrophilic vascular reaction after intradermal trauma), arthritis, thrombophlebitis, erythema nodosum-like cutaneous lesions, and neurologic signs and symptoms ranging from benign intracranial hypertension to a condition resembling multiple sclerosis. The author discusses epidemiology, diagnosis, clinical aspects, pathology, clinical course of the disease, and therapy.