Subpectoral biceps tenodesis using an interference screw is frequently used to treat biceps-related shoulder pain. Limited reports assessing complications from this procedure describe persistent bicipital pain and failure of fixation as the most common, but still infrequent complications. We believe that with increased use of the subpectoral biceps tenodesis technique more complications may become evident. The purpose of this study is to provide the first anatomic description of at-risk structures during subpectoral tenodesis.The subpectoral biceps approach described by Mazzocca et al (2005) was performed in 17 upper limbs using a standard incision placed in the medial one-third of the arm, centered over the pectoralis tendon. As originally described, a blunt Chandler was positioned on the medial aspect of the humerus to retract the coracobrachialis and short head of the biceps. The location of the tenodesis was consistently referenced at the medial border of the biceps and inferior aspect of the pectoralis tendon. All important anatomic structures were identified, including the cephalic vein, medial brachial cutaneous nerve of the arm and forearm, intercostal brachial cutaneous nerve, musculocutaneous nerve, axillary nerve, brachial artery and vein, radial nerve, and deep brachial artery. Superficial structures were measured relative to the skin incision and deep structures were measured from the tenodesis site.Seventeen upper extremity dissections (9 right, 8 left) were performed in 9 cadavers (6 males and 3 females). The cephalic vein was 9.2 mm ± 6.1 mm and 13.7 mm ± 5.8 mm lateral to the superior and inferior margins of the incision, respectively. The medial brachial cutaneous nerve of the arm, medial brachial cutaneous nerve of the forearm and intercostal brachial cutaneous nerves were not at risk during superficial dissection. The musculocutaneous nerve was 10.1 mm ± 3.2 mm medial to the tenodesis location and 2.94 mm ± 1.4 mm medial to the medially placed retractor. In internal rotation the musculocutaneous nerve was 8.1 mm ± 3.3 mm from the tenodesis site compared to 19.4 mm ± 8.2 mm in external rotation (p<.001). The radial nerve and deep brachial artery were 7.4mm ± 3.0 mm and 5.7 mm ± 2.9 mm deep and medial to the medially placed retractor. The median nerve, brachial artery, and brachial vein were not at risk during deep dissection.This study represents the first anatomic assessment of at-risk structures in subpectoral biceps tenodesis. The proximity of the musculocutaneous nerve to the tenodesis site and medial retractor make this a particularly vulnerable structure. External rotation of the arm moves the nerve 11.3 mm away from the tenodesis site and this maneuver should be applied during deep dissection. Additionally, although not previously described as a potential complication, the proximity of the leading edge of the medial retractor to the radial nerve and deep brachial artery is important and should be considered when placing this retractor. With increased acceptance of this procedure, more adverse outcomes related to damage of surrounding neurovascular structures are plausible but may be prevented by an improved understanding of the applied anatomy.