For the 2010Á2011 influenza season, Spokane Regional Health District required hospitals to report any admissions with laboratory-confirmed influenza using traditional NC surveillance methods. Simultaneously, HIE records from four Spokane facilities were monitored for flu diagnoses (i.e., records with ICD9 487Á488 listed in the working or final diagnoses) and positive flu laboratory test results (including rapid antigen, DFA, culture or PCR). Records from the NC system and the HIE were matched using facility name, age, gender, county and admission date. The medical records of cases detected by the HIE but not reported through the NC system were evaluated to determine true case status. Sensitivity and PPV were calculated for each surveillance system. Timeliness, completeness and representativeness of records received through the HIE were evaluated against NC reporting.