Background: Chronic rhinosinusitis (CRS) is a heterogeneous inflammatory condition of the sinonasal cavity. CRS may be preceded by other sinonasal inflammatory diseases including allergic rhinitis (AR). It is unclear what factors may predispose patients with AR to develop CRS. Methods: We performed a retrospective review of all patients diagnosed with AR (and not CRS) that presented to an otolaryngology clinic at a tertiary care center as part of a multidisciplinary allergy evaluation between March 2004 and November 2011. Medical records were evaluated for clinicodemographic factors including age, gender, smoking history, asthma, gastroesophageal reflux disease (GERD), aspirin sensitivity, nasal polyposis, seasonal AR, perennial AR, categories of positive antigens on formal allergy testing, and the following sinonasal anatomic variants on computed tomography (CT): infraorbital (Haller) cells, concha bullosa, frontal intersinus cells, and anterior ethmoid frontal recess cells. Patients who did not develop CRS after at least 4 years of follow-up were grouped into the AR cohort. Patients who developed CRS after at least 6 months of follow-up were grouped into the AR-CRS cohort. Results: We found a statistically significant association between the presence of infraorbital (Haller) cells (odds ratio [OR] = 6.27) and frontal intersinus cells (OR = 18.37) with development of CRS on both univariate and multivariate logistical regressions. Conclusion: Sinonasal anatomical variants, specifically infraorbital and frontal intersinus cells, are associated with development of CRS in patients with AR. The presence of these variants identifies patients who should be counseled on compliance with medical therapy for AR to potentially prevent progression to CRS. � 2012 ARS-AAOA, LLC.