Nine typical cases of ossifying fibroma in the tibia or fibula were retrospectively reviewed for clinical and histopathological aspects of this disease. Along with the case analysis, light and polarized microscopic examinations were performed in each case. Differential points with monostotic fibrous dysplasia were as follows; 1) ossifying fibroma begins in the significantly younger age, which is in most cases below 10 years of age, 2) it is confined to diaphysis of tibia or fibula, 3) radiologically, multilocular osteolytic destructive change in eccentric pattern is usually combined with anterior or anterolateral bowing deformity, 4) microscopically, characteristic findings are presence of osteoblastic rimming, peripheral maturation, and zonal phenomenon. In the treatment of ossifying fibroma, definitive surgical treatment should be delayed until skeletal maturity, when segmental resection in wide margin including periosteum might be preferred.