The fibular collateral ligament (FCL) is one of the larger ligaments of the knee. The FCL, along with the popliteus tendon, arcuate popliteal ligament, and joint capsule, make up the posterolateral corner of the knee. Recently, there has there been an increased awareness and research on the structures of the posterolateral corner of the knee, particularly the FCL. Studying the detailed structure of the FCL may provide a better understanding that can lead to better diagnosis and treatments following injury. Therefore, this article reviews the FCL, which appears to be the primary restraint to varus rotation but is poorly oriented to resist external rotation of the knee. Clin. Anat. 27:789–797, 2014. © 2013 Wiley Periodicals, Inc.