Oral and genital aphthae are the main clinical dermatologic manifestations of Behçet's disease. They look like those that occur in other aphthosis. Cutaneous lesions include pseudofolliculitis, folliculitis, erythema nodosum-like lesions, Sweet's-like lesions and pyoderma gangrenosum-like lesions. Histologically, these lesions are frequently perivascular with proeminent infiltrates of neutrophils and/or lymphocytes. Hypersensibility to needle pricks is explored by the pathergy test which sensibility is highly variable depending on the countries. When there is no systemic lesions requiring oral corticosteroids or immunosuppressive therapy, colchicine, aspirine, or dapsone may be prescribed. Thalidomide is sometimes required if aphthosis is refractory to other treatments despite its neurotixic and teratogenic effects.