Ossifying fibroma is a benign osteogenic mesenchymal tumor that is classified in the fibro-osseous lesions. Fibro-osseous lesions contain minerals, blood vessels, and giant cells that have the same radiographic and pathologic features but have different clinical behaviors, and were replaced with the normal bone. These lesions include fibrous dysplasia, cemento-osseous dysplasia, and ossifying fibroma. Juvenile ossifying fibroma is a type of uncommon and has invasive behavior, high incidence and occurs in young men, especially in maxilla, and is different from the type of adult in age, location, and clinical behavior and microscopic view. Pathologically, ossifying fibroma is divided into two types of trabecular and psammomatoid. The trabecular type is characterized by the presence of the osteoid trabeculae and the woven bone, and the type of psammomatoid by the presence of round, integrated, and small ossicles that are similar to the components of the psammoma. The purpose of this report is the clinical examination, radiography, pathology, and the treatment of a rare case of ossifying fibroma (trabecular) in mandible in a 7-year-old boy.