Venous lesions in Behçet's disease (BD) were defined by Adamantiades and represent one of the most suggestive signs of the disease. They are occasionally the first sign of the disease and are frequently the basis for the diagnosis in a case of recurrent thrombosis in a young subject, the preferential context of BD. Involvement of superficial vessels is virtually constant. Venous vasculitis is responsible for non-specific hypersensitivity and erythema nodosa, which constitute some of the major diagnostic criteria. Ocular periphlebitis is one of the elements responsible for posterior uveitis. The originality of the venous involvement is due to the involvement of deep territories. Any vein may be affected, but the remarkable features are the size of the thrombosed vessels: superior and inferior vena cava, iliofemoral veins and the unusual site of the involvement: supra-hepatic veins, cerebral vessels, etc. Inferior vena cava thrombosis may be associated with aneurysms of the pulmonary arteries in the context of Hughes-Stovin syndrome. Cerebral phlebitis, which can now be identified more easily by means of digital angiography, is responsible for a typical picture: headaches, bilateral papilloedema and raised CSF pressure. The classical pictures of optic chiasmatic arachnoiditis and so-called benign intracranial hypertension actually correspond to unrecognised phlebitis. They may also be associated with other neurological lesions. In one half of cases, phlebitis cutaneous manifestations. However, they may precede the diagnostic signs or may occur very late in the course of the disease. They are recurrent and affect a number of different territories.(ABSTRACT TRUNCATED AT 250 WORDS)