Intramuscular lipoma occurring in the tongue of a 37-year-old Japanese male in good health is reported. The lesion was composed of mature adipose tissue that infiltrated the muscle in a diffuse manner, and the entrapped muscle fibers exhibited varying degrees of atrophic change. There were no lipoblasts or atypical cells as in well-differentiated liposarcoma. Review of the literature yielded only three cases of infiltrating lipoma occurring in the tongue.