PURPOSE: Carpal tunnel syndrome is the most common peripheral compressive neuropathy. Most cases are idiopathic, but rarely carpal tunnel syndrome can be associated with a ganglionic mass. We report our recently encountered experience of surgical treatment of carpal tunnel syndrome caused by a simple ganglionic mass. METHODS: A 53-year-old man presented with chief complaints of numbness and hypoesthesia of his left palm, thumb, index finger, long finger, and ring finger of one and half month duration. Physical examination revealed positive Tinnel's sign without previous trauma, infection or any other events. Electromyography showed entrapment neuropathy of the median nerve. Magnetic resonance imaging(MRI) showed an approximately 2.0cm-sized mass below the transverse carpal ligament. Upon surgical excision, a 1 x 1.5cm2 mass attached to the perineurium of the median nerve and synovial sheath of the flexor digitorum superficialis and redness and hypertrophy of the median nerve were discovered. With surgical intervention, we completely removed the ganglionic mass and performed surgical release of the transverse carpal ligament. RESULTS: The pathology report confirmed the mass to be a ganglion. The patient exhibited post-operative improvement of his symptoms and did not show any complications. CONCLUSION: We present a review of our experience with this rare case of carpal tunnel syndrome caused by a ganglionic mass and give a detailed follow-up on the patient treated by surgical exploration with carpal tunnel release.