The term atypical lipomatous tumor (ALT) is synonymous with well-differentiated liposarcoma (WDL). This tumor occurs very rarely in the tongue. Thus, it is difficult to predict its prognosis. Although recurrence of ALT/WDL is thought to be unlikely after complete excision, long-term follow-up is necessary when considering the pathologic conditions of this tumor at other sites. Here, we report a case of an ALT of the tongue, with a review of the literature. A 68-year-old man was referred to our hospital because of a tumor on the left side of his tongue. Upon palpation, the tumor was 12mm in diameter, circumscribed, elastic and hard, well demarcated, movable, and painless. We diagnosed the lesion as a lipoma and extirpated the tumor under local anesthesia. Because the specimen was histopathologically diagnosed as an ALT, as a precaution, we excised an additional 5mm from the area surrounding the original tumor under general anesthesia. Three years after the operation, the tongue demonstrated good healing without paresthesia or dysfunction, and to date there has been no evidence of recurrence.