[en] The operating experience of the 250 kW TRIGA Mark-II reactor of the J. Stefan Institute in Ljubljana, Slovenia in the years 1996 and 1997 is reported. The reactor has been in operation without long undesired shut-down. In 1996 the production of energy was 401 MWh (around 1600 hours in operation) and there was 7 unplanned shut-downs because of electricity broke down. In 1997 the production of energy was 272 MWh (around 1090 hours in operation). In 1991 and 1997 the reactor was almost completely reconstructed and upgraded. The reconstruction consisted mainly of replacing the grid plates, the control rod mechanisms and the control unit. Recently, the new PC based system was adopted and developed to collect the operational radiation data of the reactor. The new wiring of the electric power system, part of the primary and secondary coolant system piping and the spent fuel storage pool have been modified and the new air-exchange system in the control room were installed. Because of this large reconstruction of the reactor, for the last years in the operation of the reactor no significant problems have been detected. The facility is expected to operate without major investment at least until 2006. The reactor has been utilized in the projects: Neutron activation analysis, Boron neutron capture therapy, Real time neutron radiography, Neutron tomography, and Dosimetry research. The activities of neutron activation analysis, neutron radiography and tomography as well as boron neutron capture therapy are shortly presented