PURPOSE: To evaluate the CT finidngs of malignant nasal cavity tumors. MATERIALS AND METHODS: Retrospective analysis was performed on 20 patients with pathologically-proven malignant nasal cavity tumors. Using CT, we analysed their location, extent of bone destruction and of involvement of adjacent structures, and enhancing pattern. RESULTS: A total of 20 cases included nine squamous cell carcinomas, three olfactory neuroblastomas, three lymphomas, two polymorphic reticulosis, one adenoid cystic carcinoma, one undifferentiated carcinoma and one metastasis from renal cell carcinoma. All cases except one adenoid cystic carcinoma and one squamous cell carcinoma revealed bone destruction or erosion. Aggressive bone destruction and irregular enhancement were seen in eight cases of squamous cell carcinoma, seven cases of which showed involvement of the adjacent paranasal sinuses, nasopharynx, and orbit. Olfactory neuroblastomas were centered in the superior nasal cavity and the adjacent ethmoid sinus, and had erosion or destruction of the cribriform plate had occurred. Lymphomas showed bilateral involvement, with uniform contrast enhancement. Polymorphic reticuloses showed perforation or erosion of the nasal septum with bilateral involvement of the nasal cavity. CONCLUSION: The location, presence of bone destruction, involvement of adjacent structures, and enhancement pattern of tumor on CT can be helpful for the differential diagnosis of malignant nasal cavity tumors.