Separate questionnaires regarding surgically treated complications of endoscopic and open carpal tunnel release over a 5-year period were sent to members of the American Society for Surgery of the Hand to assess and compare major complications of the 2 procedures. Four hundred fifty-five major complications from endoscopic carpal tunnel release were treated by the 708 respondents. This included 100 median nerve lacerations, 88 ulnar nerve lacerations, 77 digital nerve lacerations, 121 vessel lacerations, and 69 tendon lacerations. There were 283 major complications from open carpal tunnel release treated by 616 respondents, including 147 median nerve lacerations, 29 ulnar nerve lacerations, 54 digital nerve lacerations, 34 vessel lacerations, and 19 tendon lacerations. Although this is a retrospective voluntary study with resultant methodologic flaws, the data support the conclusion that carpal tunnel release, be it endoscopic or open, is not a safe and simple procedure. Major, if not devastating, complications can and do occur with both procedures, of which surgeons should be ever cautious.