The article will proceed through the following sections: (1) the pathophysiology of BD; (2) evidence that BD is an autoimmune disease; (3) introduction to EBV; (4) introduction to EBV‐infected autoreactive B‐cell hypothesis of autoimmunity; (5) evidence for a role of EBV in the pathogenesis of BD; (6) evidence for a role of CD8+ T‐cell deficiency in BD; (7) the benefit of sunlight; (8) the role of stress; (9) proposed hypothesis for the development of BD; (10) testing the hypothesis, including the implications for immunotherapy and phototherapy; and (11) conclusion. This evidence concerns the gene CD8A and Behcet disease.