This is a retrospective cross-sectional study conducted August 1, 2009, to July 31, 2011, in the emergency department of an academic medical center. The sample consisted of 2661 patients who received a nasopharyngeal swab followed by polymerase chain reaction (PCR) testing for respiratory viruses. Geographic Utilization of Artificial Intelligence in Real-Time for Disease Identification and Alert Notification (GUARDIAN)*a syndrome surveillance program*was utilized to review patients' records and detect the presence or absence of 37 influenza-associated symptoms (e.g., rhinorrhea, myalgias, headache and nausea among others) including reported and measured fever, cough and sore throat. Demographic factors such as age groups and gender were included in the analysis. Descriptive and x 2 test were used to determine a subset of significant signs and symptoms. A binary logistic regression with backward selection option was employed to further narrow down significant symptoms.