The role of viral infections, such as herpes simplex virus (HSV) infection, in the pathogenesis of Behçet's disease (BD) has been investigated for many years. HSV has been detected in peripheral blood leukocytes, saliva, and genital ulcers of patients with BD. Various cell adhesion molecules on cultured endothelial cells have been induced by HSV in a TNF- α dependent manner. In addition, a BD-like animal model was developed by inoculating ICR mouse earlobes with HSV, and antiviral treatment was effective in improving BD-like symptoms in this model. Still, there are several incompletely characterized proteins that possess antiviral properties and are being investigated as mediators of viral infection-related chronic inflammatory reactions. Although the role of HSV in the pathogenesis of BD remains to be fully established, recent research findings regarding HSV in BD have expanded our understanding of the disease and will hopefully lead to the development of more effective therapeutic agents in the near future.