Behcet’s disease is a systemic inflammatory vasculitis, characterised by oral ulcers, genital ulcers, skin lesions and ocular lesions. It can affect the blood vessels of almost any system involving the gastrointestinal and neurological systems. The association of HLA-B51 and Behcet's disease has been reported in patients of many ethnic groups. Approximately 20% of healthy individuals of various ethnic origins are HLA-B51 positive, compared to 50 to 80% of patients with Behcet's disease. The principal hypothesis is thus the generating of an immune response by a specific microbial or environmental antigen in a genetically susceptible HLA-B51 individual, causing in the systemic manifestations of Behcet’s disease.