The ossifying fibroma is very uncommon benign neoplasm. It is difficult to differenciate ossifying fibroma from monostotic fibrous dysplasia. In the past many authers regarded ossifying fibroma as a variant of monostotic fibrous dysplasia, but currently, many articles state that the former is another specific clinical entity. We experienced a case of ossifying fibroma involving left maxillary antrum, ethmoid sinus and nasal cavity, whitch occured in 19 years old man as a slowly growing mass with facial asymmetry. The patient managed by medial maxillectomy without evidence of recurrence.