Abstract:Methotrexate(MTX) is an antifolic agent with a well-established history of use in the treatment of various neoplastic diseases. Low-dose MTX has been widely used for rheumatoid arthritis(RA) as a disease-modifying antirheumatic drug (DMARD) . We report three cases of oral ulceration caused by an antirtheumatic drug(MTX) and a review of the literature in these cases is MTX was discontinued and the oral ulceration disappeared.