Recent advances in our knowledge of wrist ligamentous anatomy, as well as improvements in arthroscopic techniques, permit the diagnosis and treatment of a wide variety of wrist injuries. The authors review current concepts in wrist ligamentous anatomy, patterns of instability, and the role of the arthroscope in the evaluation and treatment of such instability. Specifically, wrist portal anatomy and techniques of arthroscopic treatment of patients with partial and complete intercarpal ligament injuries are described. Chronic complete injuries are a contraindication of arthroscopic treatment. The authors conclude that wrist arthroscopy provides a valuable method of diagnosing and treating partial and complete intercarpal ligamentous injuries.