This paper presents the results of a retrospective clinical study of 250 cases of monocentric carcinoma of the mucosal surface of the cheek, i.e. all the primaries treated by radiotherapy at our Institute between January 1948 and December 1965. Neoplastic lesions found at follow-up were regarded as marginal recurrences if in the proximity of the treated area and as secondary tumors in other cases. From 1948 to 1957 conventional radium therapy was the usual treatment for the primary tumor whereas from 1958 to 1965 cobalt teletherapy was given most frequently. Surgery was reserved for lymph node metastases when present on clinical examination. In our experience radiotherapy is effective in cancers of the mucosal surface of the cheek, for it checked local spread in 50.9% of cases, however treated and regardless of initial clinical appearance, whereas in the T1-T2 cases the local failure rate dropped to 35.8%. The higher the T level the greater are the difficulties confronting radiotherapy; for more extensive lesions appropriate combination therapy (radiosurgical) in line with the well-defined rules explained in the text is useful. In our experience radiotherapy yields good long term results regardless of T level and even in the more unfavorable cases. Our study confirms the low rate of lymph spread of these carcinomas: over half of the patients were N0 before treatment; only 56.7% of the patients receiving surgical treatment on the neck had histologically positive lymph nodes; there were very few neck recurrences at follow-up; the presence of suspect or frankly metastatic nodes on clinical examination, being movable and homolateral (N1), did not worsen the prognosis. However, considering the techniques used for irradiation of the primary, some patients received a substantial dose to the neck; hence radiotherapy probably played its part in the low rate of neck metastases.