The evaluation of tongue swellings often represents a diagnostic challenge, because of the wide spectrum of benign and malignant possible lesions. We report a case of a patient presenting a tongue mass. An incisional biopsy was performed. Diagnosis of primary Mantle Cell non-Hodgkin's Lymphoma of the tongue was made by histological, immunohistochemical and cytogenetic studies. Our patient was treated with Rituximab-Cyclophosphamide, Epirubicine, Vincristine, Prednisone polychemotherapy plus Rituximab as single agent maintenance. Complete remission was achieved and no relapse has occurred during a follow-up of 53 months. We emphasize the importance of including also NHL in differential diagnosis of a tongue mass.