This paper presents the ECHOES' (Educational Hypermedia On-linE System) training environment, its architecture and the services ofSered to the users. The main objective of the ECHOES project is to build a distributed dynamic environment for educating and supporting technicians in using and repairing complex industrial artefacts. To pursue this objective, ConzputerWeb Based Training, Virtual Reality and Multi-Agent Systems are integrated and synthesised in the ECHOES environment. These technologies are used to aid users at different levels of complexity, starting from the novice, who wants to quickly develop a global functional view of complex systems, up to the technician, who needs a strong conceptual understanding of complex equipment. The user interaction with the system is agent based and the chosen inteface is that of the visit metaphor within a 2 0 or 30 environment, in order to leave the trainee or the technician free in exploring the environment.