Allergy is an important consideration in the evaluation of patients with rhinosinusitis. Several studies have addressed staging systems for rhinosinusitis based on the extent of disease present on computed tomography (CT) scanning. The severity and extent of sinus disease present on CT imaging helps guide decisions regarding medical and surgical treatment options. This study evaluates the severity of sinus disease in allergic and nonallergic patients. A total of 42 patients at our institution underwent both modified RAST and coronal sinus CT scan in the evaluation of their rhinosinusitis symptoms. A single, blinded staff neuroradiologist staged all 42 CT scans using the Lund-Mackay staging system. None of the patients had undergone sinus surgery. Age, sex, co-morbidities, asthma, smoking, RAST score, total IgE, and CT staging score were analyzed. Allergic patients were found to have a higher CT scan score (mean score = 12) when compared to nonallergic patients (mean score = 6), indicating more extensive sinus disease (p = 0.03). We conclude that allergy is a significant factor in the development of rhinosinusitis, and allergic patients are more likely to demonstrate advanced disease on CT scan when compared to nonallergic patients.