PURPOSE: Recently, paranasal sinus(PNS) CT has increasingly been used because of the wide applications of a functional endoscopic sinonasal surgery(FESS) as one of the therapeutic modalities of the chronic sinonasal inflammatory disease. MATERIALS AND METHODS: We retrospectively analyzed PNS CT findings in 76 patients with chronic sinonasal inflammatory disease who had undergone the PNS CT from April 1991 to July 1992. RESULTS: There were 5 sinonasal patterns of inflammation ;4 cases of infundibular type(5.3%), 14 cases of ostiomeatal unit(OMU) type(18%), one case of sphenoethmoidal(SER) type(1%), 56 cases of sinonasal polyposis type(74%), and one case of sporadic type(1%). The mucosal abnormality was seen in 74 OMU cases, 71 maxillary sinus cases, 69 ethmoidal sinus cases, 55 frontal sinus cases, 49 SER, and 46 sphenoidal sinus cases. The normal bony variant included ethmoid bulla(25 cases, 335), concha bullosa (20 cases 25%), Hailer cells(10 cases, 13%), paradoxical curvature of middle turbinate (4 cases, 5%), lateral deviation of uncinate process(3 cases, 4%), and deviation of nasal septurn(31 cases, 41%). CONCLUSION: The PNS CT is an excelleht imaging method providing detailed informations about the mucosal abnormality, pathological pattern, the anatomical structure and landmark, and bony variants prior to an operation.