To better control anterolateral rotational instability (ALRI) after anterior cruciate ligament reconstruction (ACLR), many recent studies have examined the anterolateral ligament (ALL). Although some inconsistencies have been reported, anatomic studies demonstrated that the ALL runs on the lateral side of the knee from the femoral lateral epicondyle area to the proximal tibia, between Gerdy's tubercle and the fibula head. Histologic research has characterized the ALL structure, which is more than a simple capsular thickening; it shows a dense collagen core, typical bony insertions and mechanoreceptor function. An analysis of biomechanical properties suggests that the ALL is weaker than other knee ligaments. While its contributions to tibial anterior translation control and to a high grade on the Pivot-Shift test are still unclear, there is a consensus that the ALL controls tibial internal rotation. Further research will be needed to clarify the significance of ALL injuries and to gauge the value of combined ACL and ALL reconstructions.