Abstract:[Objective] To introduce the surgical techniques and preliminary outcomes of endoscopic decompression with facet process preservation for thoracic ossification of ligamentum flavum. [Methods] A total of 24 patients underwent abovementioned surgical treatment for thoracic ossification of ligamentum flavum. The patient was paced in prone position, and local anesthesia combined with intravenous anesthesia were used. Under C-arm fluoroscopy, a trephine was inserted onto the facet process medial margin of the affected segment. As the endoscopic system was connected, partial ipsilateral laminectomy was conducted to expose the dura with the visualizing trephine. By using laminar rongeur and grinding drill, the ipsilateral lamina was completely resected cephalocaudally. Furthermore, the contralateral lamina was removed under the base of the spinous process, and the ossified ligamentum flavum involving the spinal canal were separated and excised gradually to finish decompression to both sides of the dural edge, 1 cm above and below of the ossified ligament to regain dural pulsation. After complete hemostasis, the incision was closed in layers. [Results] All the patients were operated successfully with no serious complications, such as dural tear, nerve and blood vessel injury. Compared with those preoperatively, VAS score [(6.2±0.9), (1.6±0.7), (1.5±0.5), P＜0.001], ODI score [(55.4±8.2), (18.6±3.1), (8.5±1.2), P＜0.001] significantly improved 3 months postoperatively and at the latest follow-up. Based on the modified Macnab's criteria, the excellent and good rate of clinical outcomes was of 83.3%. [Conclusion] This endoscopic decompression with facet process preservation for thoracic ossification of ligamentum flavum is a safe and effective surgical procedure with advantage of sufficient decompression of the spinal canal and avoiding iatrogenic segmental instability in the later stage.