No randomized trials have compared long-term outcomes following endoscopic and open carpal tunnel release in patients with carpal tunnel syndrome (CTS). The investigators conducted a single-center randomized controlled trial between January 1998 and December 2002, including 128 patients (25 to 60 years) with clinically diagnosed and electrophysiologically confirmed idiopathic CTS. The outcome measures included the validated CTS symptom severity and functional status scales completed at baseline and 1 year postoperatively. The trial showed that the 1-year outcomes of open and endoscopic carpal tunnel release regarding symptoms and function were equivalent. This extended follow-up of the randomized trial will primarily measure the symptom outcomes at 10-15 years after surgery. A questionnaire will be sent by mail to the patients. The questionnaire will consist of the CTS symptom severity and functional status scales, the 6-item CTS symptoms scale (CTS-6), the 11-item disabilities of the arm, shoulder and hand (QuickDASH), the 2-item palmar pain scale, and a visual analog scale about treatment satisfaction. The patients will also be asked about whether they had undergone further surgery for CTS in the same or contralateral hand after their operation in the randomized trial. The completed questionnaires will be scanned into a database. The scores for the different scales will be calculated. Analysis will include comparison between the open and endoscopic groups as well as within-group changes of scores from 1 year to 10-15 years.