Behçet's disease is a systemic vasculitis characterized by recurrent oral and genital ulcers, and ocular inflammation, and which may involve the joints, skin, central nervous system and gastrointestinal tract. It is most common in those of Mediterranean and Eastern origin, although it also affects Caucasians. The aetiology of the disease remains unknown, but the most widely held hypothesis of disease pathogenesis is that of a profound inflammatory response triggered by an infectious agent in a genetically susceptible host. Supporting this is the consistent association of disease susceptibility with polymorphisms in the human leukocyte antigen complex, particularly HLA-B*51. The diagnosis is a clinical one, and although there is no single laboratory test specific for the diagnosis of Behçet's disease, the 1990 classification criteria perform well in a clinical context. Whereas many favoured treatments for single or multisystem disease still lack a sound evidential base, cyclosporin and azathioprine perform well in clinical trials, and evidence is accumulating for the efficacy of anti-tumour necrosis factor therapy in particular clinical situations. This review will focus on recent developments in the understanding of disease pathogenesis and clinical diagnosis, and review the evidence base for both established and new agents in the therapeutic strategy.