CT findings of histologically proven malignant tumors of maxillary sinus in 36 patients were retrospectively analyzed. A variety of malignant tumors were included; 27 cases of squamous cell carcinoma, 3 malignant lymphomas, 2 malignant melanomas, 2 rhabdomyosarcomas, and chondrosarcoma, adenoid cystic carcinoma. and malignant ameloblastoma. CT staging was T4 in 19 cases, T3 in 16 cases and T2 in 1 case. The most common involved area beyond maxillary antrum was nasal cavity, followed by ethmoid sinus, orbit, infratemporal fossa, cheek skin, pterygopalatine fossa, and nasopharynx. Skeletal destruction was seen in medial wall of antrum, posterior wall of antrum, anterior wall of antrum, roof of antrum, lamina papyracea, and lateral wall of orbit in that order of frequency. Lymph node matastases werefound in 2 cases of malignant melanoma, 2 cases of malignant lymphoma, and chondrosarcoma, squamous cell carcinoma, and malignant amelobglastoma. Predilection site of lymph node involv ment was submandibular, internal jugular, parotid, and retropharyngeal node.