In 1997, the Task Force on Rhinosinusitis produced a working definition for adult chronic rhinosinusitis. The diagnostic criteria grew out of expert consensus opinion and were "intended to serve as a unifying starting point for further research." The validity of these criteria has not been tested yet. This article summarizes our experience with these diagnostic criteria. All patients presenting for evaluation of rhinosinusitis were routinely questioned as to the presence of a number of sinonasal symptoms, including those contained within the Task Force's working definition. The presence or absence of nasal purulence on anterior nasal examination was noted also. Patients who subsequently had surgery to address their chronic rhinosinusitis were felt to be the "gold standard" and comprised the study population. All patients included in the study had symptoms for > 12 weeks, evidence of rhinosinusitis that was discovered by computed tomography (CT), and inflammation found on analysis of pathology specimens. These patients' symptom questionnaires and nasal examinations were reviewed. Fifty-seven patients met the criteria for inclusion in the study. Nasal obstruction/blockage and facial congestion/fullness were the most common symptoms. The average numbers of major and minor symptoms were 3.2 and 2.8, respectively. Patients with polyps and with previous nasal or sinus surgery differed little from the overall population. Of the 57 patients in the study, 50 patients met the diagnostic criteria set forth by the Task Force for a sensitivity of 87.7%. Diagnosing chronic rhinosinusitis without radiological imaging or nasal endoscopy is difficult. The criteria set forth by the Task Force provide a relatively sensitive working definition of chronic rhinosinusitis. Further work is underway to assess the specificity and predictive value of these criteria.