Among studies evaluating minimally invasive surgical (MIS) decompression of the L5 root, techniques involving transtubular endoscopic decompression under O-arm navigation are rare. We present the case of a 68-yearold woman with left leg pain, muscle weakness and gait disturbance of one month duration. The patient underwent transtubular endoscopic decompression under O-arm navigation. There is no radiation hazard to the operating room staff with this procedure. After surgery, the patient had significant pain relief and her left lower limb motor function had improved by follow-up at one year. C-arm-free endoscopic L5 root decompression is a safe and effective procedure.