A ganglion inside the tarsal tunnel can compress the tibial nerve, leading to posterior tarsal tunnel syndrome. Classically, the ganglion is resected with an open approach. This requires release of the flexor retinaculum and dissection around the tibial neurovascular bundle, which may induce fibrosis around the tibial nerve. Endoscopic resection of a tarsal tunnel ganglion via a posterior approach has been reported. The purpose of this Technical Note is to describe the medial approach of endoscopic ganglionectomy of the tarsal tunnel. This is indicated for tarsal tunnel ganglia compressing the tibial nerve and extending to the flexor retinaculum. It is contraindicated if there is other pathology of the tarsal tunnel that demands open surgery; the ganglion compresses the tibial nerve from its deep side and does not extend to the flexor retinaculum; or in the presence of intraneural ganglion of the tibial nerve.P osterior tarsal tunnel syndrome refers to damage to the tibial nerve underneath the flexor retinaculum at the medial side of the ankle. 1 It can be idiopathic due to various lesions leading to direct trauma to the nerve or compression of the nerve by various space-occupying lesions within the tarsal tunnel, including osteophytes, exostosis, tenosynovitis, rheumatoid arthritis, schwannoma tumors, ganglia, convoluted vessels, hypertrophic or accessory muscles, and tendons. 1-3 A ganglion arising from the adjacent joints or tendon sheaths is the cause of tarsal tunnel syndrome in up to 8% of the cases. 1,4,5 Surgical treatment is indicated if the symptoms are intractable and the diagnosis is well established. 1 Although the operative outcome of tarsal tunnel syndrome caused by space-occupying lesions is more favorable than those caused by other reasons, 6 recent studies show that the results are less favorable than expected. [7][8][9][10]