A prospective study involving eight institutions was performed, incorporating 640 cases of carpal tunnel release using a dual portal endoscopic technique. The original transbursal technique described by Chow was used in 110 cases (17%), and the modified extrabursal technique was used in 530 cases (83%). An overall complication rate of 11% was found in the patients in whom the transbursal technique was used, compared with 2.2% in the patients in whom the extrabursal technique was used. The return-to-work status was followed in 291 cases (199 non-worker's compensation cases and 92 worker's compensation cases). The worker's compensation patients returned to work in an average of 57 days, compared with 22 days for non-worker's compensation patients. This study suggests the extrabursal dual portal endoscopic technique is associated with fewer complications than the transbursal approach, and patients covered by worker's compensation return to work later than non-worker's compensation patients.