This study examines the intra-articular anatomy and safe zones for arthroscopic resection of the common extensor origin for the treatment of lateral epicondylitis. The extensor complex was arthroscopically debrided in 7 cadaveric elbows to determine the percentage of each tendinous origin that was resectable. Elbow stability was assessed, and safe zones of resection were determined. The extensor carpi radialis brevis and extensor digitorum communis origin was resected a mean of 100% and 90%, respectively. Elbow stability was maintained when resection did not extend posteriorly to an intra-articular line bisecting the radial head. Posterolateral rotatory instability occurred when debridement was continued posteriorly to the axis of the radial head. In conclusion, complete resection of the extensor carpi radialis brevis-extensor digitorum communis common origin is achievable via standard arthroscopic techniques. The lateral ulnar collateral ligament remains intact and elbow stability is maintained when debridement of the extensor origin does not extend posteriorly to a line bisecting the radial head.