Background: Subscapularis insufficiency is a debilitating condition with few treatment options. Historically, pectoralis major tendon transfer has been suggested when the subscapularis tendon or muscle is deemed irreparable; however, the results of this salvage procedure have been mixed. Methods: A comprehensive review of the peer-reviewed literature addressing pectoralis major tendon transfers was performed. The clinical presentation, relevant anatomy, biomechanical rationale, surgical indications, technical considerations, reported outcomes, and significant complications are reviewed in this report. Where possible, attempts at direct comparison of outcomes among surgical techniques and surgical indications have been made. Results and Conclusions: Despite the heterogeneous reporting of clinical results, it is clear that surgical indications affect outcomes. Specifically, isolated subscapularis insufficiency shows the best prognosis with pectoralis major tendon transfer. Patients with anterosuperior instability after large rotator cuff tears or shoulder arthroplasty have the least predictable pain relief and worse functional outcomes. Level of evidence: Review Article. (C) 2014 Journal of Shoulder and Elbow Surgery Board of Trustees.