Behçet disease is characterised by a triple symptom picture (genital and oral aphthae, ocular lesions) named after the Turkish dermatologist, Hulusi Behçet. It is found all over the world, but is particularly frequent in Japan and the Mediterranean basin. Adult males are primarily affected. The classic symptomatological triad may be accompanied by other manifestations involving the skin (hypersensitivity to microtrauma is a peculiar feature), joints, nervous system, gastroenteric system, cardiovascular system (phlebitis, phlebothrombosis), lungs and kidneys. There is a chronic course marked by periods of exacerbation and remission, which may last for years. Diagnosis is clinical only, since neither the laboratory data nor the histopathological signs of vasculitis are truly pathognomonic. The prognosis quoad valetudinem is uncertain with regard to the eye lesions, which may result in blindness. The prognosis quoad vitam is usually good, though it is poor if the nervous system is involved, or in the event of lung and large vessel lesions, since death may occur from haemoptysis or the rupture of aneurysms.