OBJECTIVE To compare computed tomography (CT) scores and nasal eosinophilia between patients with allergic rhinitis and nonallergic rhinitis with eosinophilia syndrome (NARES) and to evaluate the effect of the number of responsible allergens on the CT scores. METHODS Sixty-three patients with a positive skin prick test, 11 patients with NARES and 15 healthy volunteers were included in this study. Allergic rhinitis patients were divided into three groups according to sensitivity to one allergen, two allergens, and more than two allergens. All the patients were examined by paranasal CT scans. The mean CT scores were determined by using the Lund-Mackay grading system and the results were compared. RESULTS The mean CT scores were 5.4+/-5.8, 15.6+/-6.2, and 1.0+/-0.6 in patients with allergic rhinitis and NARES and in the control group, respectively. The mean CT score and eosinophilia in nasal smears were significantly higher in NARES patients compared to those with allergic rhinitis (p<0.05). No significant differences were found between the three groups of allergic rhinitis in this respect (p>0.05). CONCLUSIONS Although the paranasal sinuses are affected by both allergic rhinitis and NARES, this effect is greater in NARES. The number of allergens causing sensitivity does not influence the CT score.