Malignant lymphomas in the head and neck region rarely occur in the oral cavity, but frequently develop in the cervical lymph nodes or Waldeyers’ring initially. We report a case of a malignant lymphoma of the margin of the tongue. The patient was an 82-year-old woman with a painless tumor arising in the right margin of the tongue. Clinical examination showed that the lesion was covered with normal mucosa. The tumor was elastic hard with a clearmargin and was movable. We diagnosed the lesion as a benign tumor of the right margin of the tongue and extirpated the tumor under local anesthesia. The specimen was histopathologically diagnosed as a non-Hodgkins’lymphoma, diffuse large B cell type. Consequently, we transferred the patient to the department of internal medicine,where she received chemotherapy with R-THP-COP, leading to remission. The remission was maintained, and there was no evidence of abnormalities. However, the patient died of acute cardiac insufficiency 1 year 9 months after the completion of chemotherapy.