ObjectiveDetermine whether the elimination of pain improves accuracy of clinical diagnostic criteria for adult chronic rhinosinusitis. Study DesignRetrospective cohort study. MethodsHistory, symptoms, nasal endoscopy, and computed tomography (CT) results were analyzed for 1,186 adults referred to an academic otolaryngology clinic with presumptive diagnosis of chronic rhinosinusitis. Clinical diagnosis was rendered using the 1997 Rhinosinusitis Taskforce (RSTF) Guidelines and a modified version eliminating facial pain, ear pain, dental pain, and headache. ResultsFour hundred seventy-nine subjects (40%) met inclusion criteria. Among subjects positive by RSTF guidelines, 45% lacked objective evidence of sinonasal inflammation by CT, 48% by endoscopy, and 34% by either modality. Applying modified RSTF diagnostic criteria, 39% lacked sinonasal inflammation by CT, 38% by endoscopy, and 24% by either modality. Using either abnormal CT or endoscopy as the reference standard, modified diagnostic criteria yielded a statistically significant increase in specificity from 37.1% to 65.1%, with a nonsignificant decrease in sensitivity from 79.2% to 70.3%. Analysis of comorbidities revealed temporomandibular joint disorder, chronic cervical pain, depression/anxiety, and psychiatric medication use to be negatively associated with objective inflammation on CT or endoscopy. ConclusionClinical diagnostic criteria overestimate the prevalence of chronic rhinosinusitis. Removing facial pain, ear pain, dental pain, and headache increased specificity without a concordant loss in sensitivity. Given the high prevalence of sinusitis, improved clinical diagnostic criteria may assist primary care providers in more accurately predicting the presence of inflammation, thereby reducing inappropriate antibiotic use or delayed referral for evaluation of primary headache syndromes. Level of Evidence4. Laryngoscope, 127:1011-1016, 2017