A case of osteogenic sarcoma of the ethmoid sinus is reported in a 45 year old man. The tumour extended superiorly through the frontal sinus and involved the medial wall of the left orbit causing diplopia. Treatment comprised partial excision followed by radiotherapy and chemotherapy with symptomatic improvement, although 13 months later the patient died from progressive local and metastatic disease. A possible relationship to previous radiation exposure is discussed.