Intra-osseous lipoma is extremely rare in the jaw bones. Characteristic histopathological finding consists of the presence of only mature adipose cells. The majority of jawbone intra-osseous lipomas are found in adults, and of uncertain origin and etiology but are usually associated with molar teeth. We present here a case of a fifteen-year-old boy who experienced a painless, gradual swelling of the right side mandibular angle for 3 years. We also discuss and compare this case with the other intra-osseous lipoma cases.