OSIRIS, one of the french C.E.A. research reactors, is located at SACLAY - PARIS, near research teams and inspection laboratories with considerable technological infrastructure. Since 27 years, the reactor is safely running and is mainly devoted to technological irradiations or examinations and radioisotopes or doped silicon production. To guarantee the safety and the high performances of the reactor, a continuous maintenance and improvement programme has taken place during the whole life of the reactor. This paper -briefly describes the reactor and recalls its main characteristics, summarizes the main points of the 27 years long reactor life, - projects the maintenance programme to the future, - gives an overview of the experimental capabilities. The facility is completed by: - the reactor ISIS, the mock up of OSIRIS, which is employed for testing new core configurations, new fuel elements or irradiation experiments using reactivity effects, neutron flux or gamma ray heating, - two hot-cells with possibility of direct under water transport of activated materials from or to one of the reactors. (authors).