To provide an aid in differential diagnosis of nasomaxillary lesions by CT appearance bony changes, we retrospectively evaluated 82 computed tomographic(CT) examinations of 79 patients who had nasomaxillary lesions(56 tumors, 23 inflammations). The bony changes were classified as destruction, displacement, and sclerosis. Destruction of bony maxilla was most common is malignancy, in which more than 3 walls were often destroyed. Displacement of bony maxilla was most common in benign tumors and in slowly-growing malignant tumors such as adenoid cystic carcinoma or lymphoma, and there was often associated bony distruction of other walls. Sclerosis was a common findings in the inflammatory process, especially in chronic mixillary sinusitis with bony destruction at the ostium of the medial wall. Sclerosis often occurred after radiotherapy and/or chemotherapy of tumors and was also noted when there was associated inflammation. Maxillary cysts showed characteristic expansion of all sinus walls. Bony changes were less prominent in the tumors of the nasal cavity compared to the changes seen in the maxillary lesions. A cardful analysis of CT findings is very helpful in differentialting malignant from benign tumors and inflammatory disease in nasomaxillary lesions.