OBJECTIVES: Minimal Access Spinal Technologies (MAST TM) potentially allows surgeons to treat back pain and disability with the least amount of interruption while achieving the same surgical objectives as open surgeries. This single center resource use utilization study was designed to assess difference between MAST TM and open surgery in hospital length of stay and its associated costs from a hospital perspective. METHODS: This study aims at comparing the average length of hospital stay (LOS) of patients treated with MAST TM in the Foch hospital and the average National LOS of patients treated with open surgery. All patient operated with MASTTM in 2007 in Foch hospital were retrospectively analyzed and were indirectly compared with patients from the National French DRG data base called PMSI. MASTTM and open surgery patients were matched on procedure code. Cost per hospital stay has been assessed with the French National Cost Study (ENC). RESULTS: In 2007, Foch hospital performed 250 MAST surgeries. The two main procedures were posterior lumbar arthrodesis (procedure code LFDA004/0; n = 68) and removal of herniated disc (procedure code LFFA002/0; n = 111). For posterior lumbar arthrodesis surgery, the average LOS in Foch Hospital was 5.9 days compared to 8.9 days in the national data base (34% decrease). For herniated disc surgery, the average LOS in Foch hospital was 3.4 days compared to 5.3 days in the national data base (36% decrease). In 2007, Foch hospital avoided 215 days of hospitalization with the MAST, representing between €133,000 and €141,000 (€320- €340 per day). CONCLUSIONS: By lowering morbidity and reducing recovery time, MAST TM reduces costs of hospital stays. The reduction of hospital days may off-set any additional device costs. Further prospective research should be considered to validate our findings; however this is one of the first studies investigating systematically this subject.