BACKGROUND: Desquamative gingivitis (DG) is a descriptive term used to indicate epithelial desquamation, erythema, erosions, and/or vesiculobullous lesions of the gingiva. DG is commonly associated with several mucocutaneous disorders and systemic conditions that may carry a poor prognosis and high morbidity; however, there are no clear data concerning the frequency of these disease associations. METHODS: We investigated the epidemiologic features of DG in 125 patients and compared our findings with information from a literature review. RESULTS: In our series, 88% of patients with DG had one of the following three disorders: oral lichen planus (OLP), mucous membrane pemphigoid (MMP), or pemphigus vulgaris. The most common cause of DG was OLP (75% of patients). 22% of patients had isolated gingival involvement, and there were diffuse gingival lesions in 57% of patients. Symptoms ranged from none (1%) to severe pain (10%). There was extra-oral involvement of skin in 14% of patients, conjunctiva in 7%, genital mucosa in 26%, and internal organs in 3%. Our study showed MMP to be associated with DG in only a small percentage of patients (9%); this finding may be related to the patient population, epidemiology of the specific disease, and referral and/or past diagnostic bias. CONCLUSION: Based on our series and recent reports, OLP seems to be the most common cause of DG.