Background: Patients with atrophic rhinosinusitis have intractable upper airway symptoms that result from loss of the normal nasal epithelium. There is no consensus on how to diagnose this condition, and diagnostic criteria are not available to perform multicenter treatment trials. We sought to establish diagnostic criteria for atrophic rhinosinusitis. Methods: Twenty-two patients for whom there was a consensus on the diagnosis of atrophic rhinosinusitis were compared with a control group of 22 randomly selected patients with garden-variety chronic rhinosinusitis. Medical records were reviewed on all patients and clinical data were tabulated. Clinical variables included the presence of nasal obstruction, epistaxis, anosmia, purulence, crusting, chronic inflammatory disease involving the upper airway, and multiple sinus surgeries. Results: Both groups had similar degrees of persistent nasal obstruction (82% vs 77%). The other 6 clinical features occurred more frequently in patients with atrophic rhinosinusitis than controls (P <.05). Patients with chronic rhinosinusitis and recurrent nasal purulence had a 25-fold (95% confidence interval [CI], 2.9-221.7) increased probability, those with recurrent epistaxis had a 12-fold increased probability (95% CI, 1.3-106.8), and those with 2 or more sinus surgeries had a 15-fold (95% CI, 3.5-66.7) increased probability of having atrophic rhinosinusitis. As the number of symptoms increased, there was an increasing probability of the predetermined diagnosis of atrophic rhinosinusitis (P <.05). The presence of chronic rhinosinusitis and any 2 of the 6 clinical features for 6 months or longer resulted in a sensitivity of 0.95 and specificity of 0.77 for the diagnosis of atrophic rhinosinusitis. Conclusion: The diagnosis of the common secondary form of atrophic rhinosinusitis may be made with certainty if a patient with chronic rhinosinusitis demonstrates 2 or more clinical features for 6 months and longer. These features are patient-reported recurrent epistaxis or episodic anosmia; or physician-documented nasal purulence, nasal crusting, chronic inflammatory disease of the upper airway, or 2 or more sinus surgeries. © 2009 Elsevier Inc. All rights reserved.