Study objective: Emergency department computerized triage logs might be useful for automated ED surveillance and potentially for early identification of bioterrorism events. We describe a Web-based surveillance program and its feasibility for surveillance. Methods:A Web-based surveillance program that receives computerized chief complaint data daily from a large academic urban teaching hospital and performs syndromic analysis on these data was developed. On the basis of preset limits, the Web-based surveillance program sends an alert e-mail message when the syndromic analysis reveals an increase in the number of patients in predefined symptom groups. The feasibility of this system was tested by using historical data during an influenza outbreak (December 1999 to January 2000) and applying the anthrax symptom group. Results: The Web-based surveillance program identified the influenza outbreak in the first week. Conclusion: Computerized triage logs might be a feasible method for bioterrorism and influenza surveillance. The Web-based nature of the surveillance program creates the opportunity for other hospitals to contribute data, potentially resulting in an automated network of ED computerized triage log surveillance. [Ann Emerg Med. 2003;41:447-452.]