The purpose of this study was to compare the paranasal sinus mucosal thickenings, bony changes consistent with chronic sinusitis, and bony anatomic variations detected by computed tomography (CT) in chronic rhinosinusitis patients with and without allergy. Three hundred and thirty-nine patients with chronic rhinosinusitis were analyzed for their allergic status by performing skin prick test. Two hundred and thirteen patients (62.8%) had at least one positive skin prick test (allergic patients, male/female: 85/128, mean age: 29.1 +/- 1.2). One hundred and twenty-six patients (37.2%) were included in the non-allergic group (male/female: 53/73, mean age: 31 +/- 2.2). Maxillary mucosal thickening and frontal hypoplasy were significantly more common in allergic chronic rhinosinusitis patients. Moreover, pneumatized uncinate process is apparently more common in the allergic group than non-allergic group, and statistical analysis revealed marginal significance (p = 0.0535). In conclusion CT findings of allergic chronic rhinosinusitis patients are comparable to the CT findings of chronic rhinosinusitis patients without allergy. However, presence of maxillary mucosal thickening, frontal hypoplasia or pneumatized uncinate process in the CT scan of a patient with chronic rhinosinusitis could be of clinical significance, and might guide the otolaryngologist for the evaluation of the presence of allergy.