Behçet disease (BD) is a systemic inflammatory disorder that affects the skin, mucosa, eyes, joints, blood vessels, brain, and gastrointestinal tract. The etiopathogenesis of BD has not yet been fully elucidated, but disorganized immune responses against the stimuli of environmental triggering factors have been considered to play a major role in the pathogenesis of the disease in individuals with genetic susceptibility. Human leukocyte antigen (HLA)-B*51 is known to be the main factor involved in genetic susceptibility to BD. Among the environmental factors, infectious agents in particular are thought to be important. Immunological abnormalities could thus be the cornerstone in the development of BD. Along with cytokines that play a role in disease pathogenesis, numerous other cytokines have been recently identified or have been the focus of recent studies. This contribution sheds light on the etiopathogenesis and immunology of BD in relation to the current literature.