RESUMEN
Oral lesions are one of the most important effects of autoimmune diseases. Ulcer, petechia, telangectasia and lichenoid lesions are the most common oral manifestations. Drugs used for systemic treatment can also cause the same side effects. According to the wide range of oral lesions, lack of solid status in Iran, difference in stated prevalence, treatment of rheumatoid arthritis with oral corticosteroids, cyclosporine, D-penicillamin and NSAIDs and their side effects, this project was carried out to determine the prevalence of oral lesions of rheumatoid arthritis in clinics of rheumatology of Tehran University at one year period. This descriptive-cross sectional study was performed by means of observation, clinical examination, completing questionnaire and also evaluating the 385 patients medical records in order to find oral mucosal lesions such as xerostomia and gingival hyperplasia. Sampling was made by a sequential method. After recording the finding, descriptive and analytic statistics were used to analyze the results. 156 of 385 rheumatoid arthritis patients [365 male and 20 female] had oral lesions [40.5%]. Xerostomia was the most common finding [14%] and gingiva, soft palate and vestibule were the most common sites reported. Due to the high frequency of oral lesions as a probable manifestation of rheumatoid arthritis and also as a side effect of its treatment must be emphasized for future