Background:Lichen sclerosus is a chronic muco-cutaneous inflammatory disorder of uncertain etiology. The prevalence of lichen sclerosus affecting only the oral mucosa is extremely rare and only 26 cases with histologically verified oral lichen sclerosus have been reported.Main observations:A 60-year-old man was referred to our hospital for complaints of white lesions in the oral cavity, which was otherwise asymptomatic and did not have any cutaneous or anogenital lesions. Clinical examination revealed white patches with reddish areas on the buccal mucosa bilaterally and on the maxillary posterior gingiva. Microscopic analysis of the lesion showed atrophied epithelium with basal cell degeneration, hyalinized connective tissue stroma with minimal chronic inflammatory cell infiltrate. Verhoeff's staining revealed scantiness of elastic fibers in the connective tissue stroma. On the basis of these histological findings, the final diagnosis was given as Lichen Sclerosus. LS is rare in the oral cavity, particularly in the absence of simultaneous cutaneous and anogenital lesions.Conclusions:Only 7 cases of oral LS have been reported involving the gingiva. To our knowledge, this is the eigth case to be reported with gingival involvement and the first case to be reported with bilateral involvement of buccal mucosa and gingiva.