Abstract The Heidelberg Ion Therapy Center HIT is in clinical operation since 2009. It is the first dedicated European particle accelerator for medical treatment. Its central location on the campus of the Heidelberg University Hospital fits perfectly in the clinical everyday life. The accelerator complex consists of a linear accelerator and a synchrotron and is designed for protons and carbon ions, but can also provide helium and oxygen ions. The LINAC, build in 2006, operates since 5 years in a 24/7 schema which leads to 60000 operating hours up to now. The performance with an availability of better than 99% is much higher than expected and is caused by a solid design and a well planned and foresighted maintenance. Unavoidable failures during operation can be solved very fast with the on site experts for each section. The combination of personnel, spare parts and permanent ongoing developments is very successful. An upgrade program for parts of the LINAC and also for the RF system is in planning to keep the up-time high and to improve the performance for further needs