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.
