Since an accurate description on the pathophysiology of the nasal cavity and paranasal sinus(PNS) was established, a detailed evaluation of their anatomic and pathologic status, especially of the ostiomeatal unit, has become important, and computed tomography(CT) has increasingly been used for evaluating chronic sinusitis. This study was undertaken to assess the value of CT in chronic or recurent paranasal sinusitis and to ascertain the theory of rhinogenic origin as the pathophysiologic basis of sinusitis. We retrospectively analyzed the PNS CT findings 108 patients with chronic or recurrent sinusitis. The CT scans were obtained in thin-secting(3mm or 5mm) coronal and axial planes after contrast medium administration. With respect to the location of the sinusitis, the anterior ethmoid sinus was involved in 98(91%), maxillary sinus in 93(86%), frontal sinus in 60(56%), posterior ethmoid sinus in 35(32%), and sphenoid sinus in 32 cases(30%). CT findings of the sinusitis consisted of sinus opacification(74%), mucoperiostea thickening(69%), mucosal enhancement(36%), air-fluid level(18%), and bony wall thickening(11%). Complications included retention cysts(29%), mucoceles(8%), and orbital cellulitis(1%). Obstruction of the ostiomeatal unit was noted in 104 cases(96%), which were composed of inflammatory process, nasal polyps, concha bullosae, inverting papillomas, paradoxic middle turbinates, severe septal deviations, and large ethmoidal bulla. Of the 17 cases with a past history of Caldwell-Luc operation, 15 cases showed obstruction of the ostiomeatal units. We concluded that CT was a very useful modality for evaluating chronic or recurrent sinusitis and for demonstrating the finely detailed pathologic anatomy of the nasal cavity and paranasal sinuses.