We present a 31-year-old female patient with Behçet's disease. Behcet's disease is a systematic vasculitis of unknown cause involving veins and arteries of all sizes and having reccurent mucocutaneous and frequent ocular involvement. Our patient was suffering from oral and genital ulcers, fever, painful left knee and erythema nodosum. After having excluded differential diagnoses Behçet's disease was diagnosed. The treatment must be individual and it depends on the presence and severity of symptoms. The optimal improvement was observed after treatment with azathioprine, cyclosporine A and metylprednisolon. Behçet's disease is very seldom in our country but perhaps sometimes it isn't good diagnosed.