Fifty-six cases of mural ameloblastoma were ananlyzed clinically and radiographically. They were transformed by ameloblastomous changes from keratocyst, occuring in 28.2% of ameloblastoma. The disease was often seen in patients of 10-29 years old with a mean of 21.8. Most of them were seen in mandible (53/56), especially in ramus (40/50). The radiographic appearance is divided into three subtypes: (1) ramus-mandibular body pattern, including dentigerous (31/56) and non-dentigerous (9/56); (2) sub-apical pattern (12/56); (3) inter-radicular pattern (4/56). The mainpoint of radiographic diagnosis is the appearance of unilocular or multilocular radiolucency of similar size, located in ramus-mandibular body or mandibular body region. The large lesions have a tendency to expand along the mandible. The roots of teeth are absorbed apparently, demonstrating serrated or amputated appearance.