Common radiographic appearances of ossifying fibroma (OF) are well demarcated margin, radiolucent or mixed lesion. Lesions for the radiographic differential diagnosis with OF include fibrous dysplasia, focal cemento-osseous dysplasia. Other confusing lesions might be the mixed lesions such as calcifying odontogenic cyst, adenomatoid odontogenic tumor, calcifying epithelial odontogenic tumor, and benign cementoblastoma. We reported three cases of OF in posterior mandible. These cases showed a little distinguished radiographic features of OF and diagnosed from a combination of clinical, radiographic, and histopathologic information. We need to further refine radiographic and histopathological features of OF and other confusing lesions with literatures review because some cases of these lesions are not easily differentiated radiographically and histopathologically.