Respiratory syncytial virus (RSV) is the most common cause of viral lower respiratory tract infection. It affects people of all ages, and can cause severe disease in infants, in older immunodeficient children and the elderly. An intriguing feature of RSV infection is the susceptibility of previously infected individuals to reinfection with antigenically closely related viruses or the identical virus strain. Recently, increased interest has been focused on the contribution of persistent RSV in several chronic lung diseases including chronic obstructive pulmonary disease [148] . The role of RSV in the physiopathology of theses disorders as well as and the mechanisms of its persistence remain to be elucidated [149] . Interestingly, in a recent work on the histopathology of untreated human RSV infection, the presence of the virus in AEC has been documented [150] . From these various data, a role of RSV in the development of ILD needs to be investigated. Immunostaining with RSV-specific antibodies of tissues from lung biopsy should be proposed.