Findings from 441 patient evaluations performed at the Taste and Smell Clinic of the Connecticut Chemosensory Clinical Research Center are presented. Taste and smell dysfunction was the chief complaint in all patients. The diagnostic approach included tests of taste and smell function; history taking; physical, neurologic, otorhinolaryngologic, and nutritional examinations; and clinical laboratory screening tests. Results indicate that the most common chemosensory dysfunction is probably olfactory: 86% of patients in this series had measurable loss of smell function. The most common cause of olfactory deficit was nasal and/or sinus disease (30% of patients), followed by idiopathic conditions (26%) and prior upper respiratory infection (19%). Assessment of individual components of the evaluation suggests that a total circulating eosinophil count may be useful as a screening test for nasal and/or sinus disease among patients whose chief complaint is chemosensory dysfunction.