The most frequently injured ligaments in the human body are the ligaments of the ligament complex located in the lateralcollateral aspect of the ankle. Therefore a thorough knowledge of anatomy and function of these structures is required to understand the mechanisms causing the instability of the ankle joint. Ligaments provide passive stability of the ankle joint, whereas active stability is provided by the support of the muscles. Since there are no muscles inserting on the talus, the stability of the talus is provided by the ligaments inserting on the talus and the neighbouring bony structures. As the anterior talofibular ligament is extremely streched in plantar flexion, it is most frequently ruptured ligament during inversion injuries. To understand the mechanism of injury of the ligaments of the ankle, it is necessary have a comprehensive knowledge about the anatomy the collateral lateral ligament, which consists of anterior talofibular ligament, posterior talofibular ligament, and calcaneofibular ligament. Understanding this mechanism is also important for the radiological and clinical diagnosis of ligament injuries and planning and performing the surgical reconstruction of these ligaments. In order to elucidate biomechanical effects of the anatomical variations of the ligaments and the importance of the role of the angle differences between the ligaments in joint stability, a precise knowledge of the normal anatomy and its associated biomechanical effects is essential.