Osteoma of the paranasal sinuses is the most commonest benign tumor orginated from paranasal sinuses and frontal sinus is the most frequent site of osteoma. The most prevalent pathogenesis is that the osteoma is a benign mesenchymal neoplasm, developing as a result of metaplasia of connective tissue with the formation of bone by the sinus mucosa acting as periosteum. Recently the authors had experienced one case of osteoma of the fronto-ethmoidal region which was removed by exernal fronto-ethmoidectomy (Lynch Frontal sinus) operation.