Autonomous Underwater Vehicles, also called "free-swimming vehicles" are self propelled bodies, equipped with their own energy package and with no solid communication link with the surface. At the beginning of the 90s, a renewed interest from the Underwater Intervention Community for autonomous vehicles and quite a number of new projects were announced or started. The present paper aims at presenting an updated State of the Art on the development of autonomous vehicles. It addresses the following points: A brief historical review presents some existing systems and uses. The French experience, in particular, allows to position the potential, and complementary contribution of autonomous vehicles, in a range of various operational systems. A short review of the main developments in the world demonstrates the particular interest for underwater robotics. An analysis of the operational aspects of these various projects leads to a distribution of the different concepts into main classes of mission profiles.