Most malignant ethmoid sinus tumors originate secondarily from maxillary sinus cancer; therefore, primary malignant tumors of the ethmoid sinus are rare. Primary malignant tumors of the ethmoid sinus have had poor prognosis, because of late diagnosis, frequent invasion to orbit and skull base and limited surgical approach. We report eight cases of primary malignant tumors of the ethmoid sinus (sarcomas, three cases; squamous cell carcinomas, two cases; adenoid cystic carcinomas, two cases; and malignant melanoma, 1 case) and discuss their treatment results.