We report one case of hereditary cherubism involving two generations. Cherubism is a rare nonneoplastic bone lesion of the jaws that causes a progressive, painless, symmetrical expansion of the maxilla and mandible. A 5-year-old boy was referred to our hospital requesting examination and treatment, with the chief complain of painless, bilateral, symmetrical swelling. In a local hospital, biopsy was performed and histological findings revealed giant cell granuloma. His mother and his uncle had been diagnosed with cherubism and were both treated surgically during childhood. Radiographs and CT images showed multilocular, well-defined, cystic spaces causing expansion of the bilateral mandibular angles and sparing only a thin layer of cortex. Radiographic findings of the mother's mandible were similar to these of the present case.