We developed a web-based evacuation site surveillance system with 8 syndromes including acute gastroenteric symptoms; influenza or influenza-like-illness; acute respiratory symptoms other than influenza; rash and fever; neurologic symptoms including tetanus, meningitis and encephalitis; cutaneous symptoms; wound-related infectious diseases; icterus and death. Age of the patients was classified into three categories: younger than 5 years, 5 to 64 years and 65 years old or older. Analysis by evacuation site was performed automatically, and if some aberrations were found, the system showed an alert sign on the screen of a computer. The information on patients was shared with the public health center and the local government office simultaneously.