Lipomais a most common benign neoplasm of mature adipose tissue in trunk and extremities. The oral cavity rarely affected by this neoplasm (1-4%) and more occurs in buccal mucosa. Floor of the mouth is rarely affected. Usually its size is less than 3 cm. The present report shows an unusualcase of large lipoma (5.5 cm in greatest dimension) in the floor of the mouth of a 68- year- old male and review of the literature.