The purpose of this article is to describe the use of the SurSaUD® surveillance system in the immediate aftermath of the Paris attacks of November 13, 2015, and to present the results of analyses conducted through the end of 2015 in the Île-de-France region and throughout France, in close collaboration with the system’s partners. Enhanced surveillance, based on the activation of automatic daily dashboards using data from hospital emergency departments (OSCOUR®) and SOS Médecins associations, as well as the implementation of a procedure to flag SOS Médecins consultations related to the attacks, was activated the day after the attacks and continued through the end of 2015. The results revealed an increase in emergency room visits for stress not only in the Île-de-France region but also across the entire metropolitan area. The tagging of SOS Médecins consultations showed a spike in activity linked to the attacks. These increases primarily affected young adults between the ages of 15 and 44. The feedback, reflections, and work that followed the attacks helped identify key areas for improving the surveillance system to increase its effectiveness, particularly in anticipation of the 2024 Paris Olympics: updating the format of the emergency department visit summary to include a circumstantial variable and integrating SAMU data into the syndromic surveillance system, to complement OSCOUR® and SOS Médecins data.