Lipomatous tumors with intramuscular infiltration are uncommon in the head and neck. Oral lipomas have been recorded in the literature; however, infiltration and recurrence have rarely been documented. We describe a case of an oral lipoma that did not have microscopic characteristics of malignancy, lipoblastomatosis, or atypia, but which showed intramuscular invasion and recurred twice after surgery. Although certain characteristics distinguish our case from congenital lipomatosis, the clinical picture is quite similar. Lipomas with intramuscular invasion uniformly tend to recur when they are not widely resected, whether in the trunk and extremities or in the head and neck. These lesions can rapidly enlarge and infiltrate local tissues, and they require wide resection with an attempt at preservation of important structures. Preoperatively, computed tomographic analysis allows a lipoma to be diagnosed by its low attenuation, and a grossly infiltrating tumor can be distinguished from the ordinary well-encapsulated lesion.