Coronal plane computerized tomographic scanning has dramatically improved the imaging of paranasal sinus anatomy. Subtle anatomic features such as Haller's cell, pneumatization or paradoxical curvature of the middle turbinate, and variations in the conformation of the ethmoid bulla, uncinate process and agger nasi cell can now be imaged through CT. As variations and anomalies of these structures have been implicated in the etiology of chronic and recurrent sinusitis, coronal plane CT imaging of the paranasal sinuses routinely has become used in the evaluation of variations are also evident on CT analysis of patients without clinical sinusitis. The true prevalence, suspected pathogenecity, and clinical significance of these bony paranasal sinus anatomic variations have therefore come into question. A detailed analysis of CT scans obtained in 101 consecutively imaged patients was conducted. The following results were obtained. 1) The incidence of sinusitis pattern was as follows : Sinonasal polyposis, OMU, Infundibular, Sporadic, Sphonoethmoidal recess in order. 2) The incidence of anatomic variation was as follows : Agger nasi cell, Septal deviation, Concha bullosa, Enlarged ethmoid bulla, Haller's cell, Paradoxical curvature of middle turbinate in order. 3) The site of insertion of uncinate process was lamina papyracea, base of skull, uncertain, middle turbinate in order.