Introduction - To ensure the epidemiological surveillance of military personnel on active duty and to detect unusual occurrences early on, the Armed Forces Health Service developed a real-time surveillance approach. The objective was to summarize the advantages and disadvantages of this approach. Methods - A real-time surveillance prototype has been in use in French Guiana since 2004. Its evaluation identified its strengths and weaknesses. This feedback made it possible to extend the concept to the surveillance of French forces stationed in Djibouti and to develop a comprehensive approach for all forces on operations. Results - Real-time surveillance demonstrated its utility for early warning during various real and simulated scenarios. Functional and architectural choices ensured interoperability with allied nations. However, the information generated constituted only one of the initial steps in assessing the epidemiological situation, necessarily followed by further investigations. Discussion - This initial development phase highlighted the complementarity with traditional epidemiological surveillance. It also identified the need to continue developing tools to account for the specific requirements of surveillance for forces in operation. (R.A.)