Forty-three human cadavers underwent single-portal endoscopic carpal tunnel release using the Agee technique. Subsequent independent open dissection revealed complete release of all potentially compressing transverse structures in 19 specimens and incomplete release in 24 specimens. There were 2 specimens with vascular injuries; one transection of a perforating branch of the palmar arch, and one transection of the ulnar artery at the entry portal. The 43 specimens were divided into three groups: group 1 (13 specimens) were released by the senior author in 1989; group 2 (13 specimens) were released by the senior author in 1992; and group 3 (17 specimens) were released by surgeons learning the technique under direct supervision of the senior author. Complete release was 5 of 13 for group 1, 6 of 13 for group 2, and 8 of 17 for group 3. This study indicates that incomplete release is an inherent feature of this technique regardless of the surgeon's experience and despite blade redesign. The significance of incomplete release is unknown and must be determined in long-term clinical studies.