It has been shown that there is a potential buccal mucomembranous hypersensitivity in persons with contact dermatitis due to penicillin.1 It has also been shown1b that topical use of penicillin in the mouth, especially with troches, can provoke stomatitis, both of the direct irritation type and the allergic contact type. The following cases of stomatitis, however, followed the administration of penicillin tablets. The patients improved rapidly when the antibiotic was discontinued, and the reactions were correlated with positive contact reactions of the buccal mucosa in tests with crystalline penicillin. With the relatively short period of contact with the buccal mucosa, it is surprising that such contact stomatitis reactions can occur. REPORT OF CASES Case 1 (Stomatitis following prolonged oral therapy with penicillin tablets).— O. M., a 44 year old white woman, was first admitted to the Cincinnati General Hospital in 1934, with discoid lupus erythematosus. Since that time she