Oral lichen planus (OLP) is a chronic inflammatory disease of the oral mucosa. It affects between 0.5% and 4% of the adult population and has a higher prevalence in middle-aged females.The pathogenesis of OLP remains uncertain, but it is thought to arise from an immune response to a number of antigens within the oral epithelium. A variety of risks or predisposing risk factors have been identified for OLP, which include periodontal and gingival inflammation arising from deposits of plaque and calculus, hypersensitivity to amalgam and other metals, trauma to oral mucosa and stress. There is also evidence that in certain population, viruses (mainly hepatitis C) may be important in the immunopathogenesis of OLP.Different forms of OLP have been recognized, which relate to clinical appearance. The current classification describes three major forms: reticular ⁄ hyperkeratotic, atrophic ⁄ erythematous and ulcerative ⁄ erosive forms.The symptoms arising from OLP vary markedly and often relate to the specific category. Pain and soreness, which interfere with oral function, are more commonly associated with the ulcerative form. Other symptoms related to OLP include soreness on tooth brushing, burning mouth and oral discomfort arising from eating hot, cold or spicy food. A range of treatments have been evaluated in the management of OLP. Topical medications seem to be the most widely used; however, a Cochrane review failed to identify a superior agent for the management of this common condition. Despite this finding, many reviews of the treatment of OLP suggest that topical steroids are the most widely used. Eleven patients suffering from symptomatic oral lichen planus were included in the present study divided into two groups. Patient were divided randomly into two groups, before and after treatment with topical Triamcinolone acetonide (0.1% in orabase(Group I: This group included 12 healthy normal and individuals free from any inflammatory oral lesions and free from any systemic diseases age (25-35y)Group II-a: This group included 11 patients (7 females and 4 males) suffering from erosive or atrophic lichen planus age (39-65y).Group II-b: This group included the same patients after topical corticosteroid therapy in the form of Triamcinolone acetonide (0.1% in orabase)*. The patients were advised to apply the drug topically to the oral lesions 4 times / day. i.e. following each meal and at bed time, for 4 weeks (Laeijendecker et al., 2006).The aim of the present study is to determine the presence of circulating autoantibodies against desmoglein-1 in patients with erosive forms of OLP and the role of corticosteroid therapy on the expression of these autoantibodies. Peripheral blood for determination of circulating autoantibodies was drawn from each participant between 8 am and 9 am. Serum was separated and stored in several samples at -20°C until use. Repeated freeze-thawing was avoided.Commercial enzyme-linked immunosorbent assay (ELISA, Medical and Biological Laboratories Co. Ltd, Nagoya, Japan) was used to determine autoantibodies to desmogleins 1 (MESACUP Desmoglein test [Dsg 1], Code No. RG-M7593-DThe results of the present study revealed that the age of OLP patients raged from 39-65y with a mean value of 52.5y.Concentrations of anti-desmoglein 1 autoantibodies in the patients were significantly higher in patients with erosive form of oral lichen planus than in healthy controls (P<0.001).Increased concentrations of anti-desmoglein 1 autoantibodies, which were detected in the sera of patients with erosive form of oral lichen planus indicated that anti-keratinocyte autoantibodies may be involved in pathogenesis of this clinical form of oral lichen planus. The results of the present study revealed that topical corticosteroid had significant effect in the treatment of the patient.