Symmetrical lipomatosis is characterized by symmetrical infiltration of adipose tissue into the head, neck, or upper trunk. By contrast, oral involvement is extremely rare. The present report describes a case of symmetrical lipomatosis of the tongue (SLT) presenting as macroglossia. The patient was a 63-year-old Japanese male who developed progressive dysarthria secondary to enlargement of the tongue. The patient's medical history was notable for alcoholic hepatitis and hyperlipidemia. Marginal glossectomy was performed on both sides of the tongue to achieve volume reduction and restore normal speech. Histopathologic examination of the resected tissue revealed diffuse infiltration with adipose tissue lacking a fibrous capsule. The patient's postoperative course was uneventful, and he remained free of recurrence or regrowth and functional deficits at the 6-year follow-up time point.