Abstract: Benign lymphoepithelial lesion (BLEL) is known as Mikulicz disease. The clinical manifestation of BLEL mainly includes diffuse painless enlargement of unilateral or bilateral lacrimal gland or salivary gland. There are many different perspectives to analyze the pathogenesis including pathology, infection, immunology, epidemiology and molecular biology. Currently, the proposed theories for its etiology include basal cell hyperplasia invasion, virus intervention, autoimmune dysfunction, sex hormone dysregulation, protein disorder,  and IgG4 invading etc, however still a lot of controversies.  More researches need be conducted. (Int Rev Ophthalmol, 2014, 38: 208-211)