Behçet's syndrome (BS) is a systemic vasculitis of unknown etiology. There are several reasons for doubting a primary autoimmune pathogenesis of this condition. Recent information suggests evidence for genetic anticipation. Although there is heightened inflammatory activity, as exemplified by the pathergy reaction, wound healing in BS is normal. BS also runs a more stormy course in adults and in the young. However, the amount of androgen receptors in scrotal skin have not found to be increased. Another unsolved problem is the nature of acne-like lesions and how they differ from acne vulgaris (AV). Only lesions in "non-acne" areas were compared between the two conditions, and no differences were detected. Mortality is increased in BS, especially among males. Azathioprine proved to be effective in disease control after 8 years of follow-up. We have also recently finished a 24 week controlled trial of two doses of thalidomide, 100 mg and 300 mg per day. Both doses were superior to placebo, with no real differences in efficacy, in controlling the oral and genital ulcers.