Acute ankle ligament sprains are common injuries. The majority of these occur during athletic participation in the 15 to 35 year age range. Despite the frequency of the injury, diagnostic and treatment protocols have varied greatly. Lateral ligament complex injuries are by far the most common of the ankle sprains. Lateral ligament injuries typically occur during plantar flexion and inversion, which is the position of maximum stress on the anterotalofibular liagment (ATFL). For this reason, the ATFL is the most commonly torn ligament during an inversion injury. In more severe inversion injuries the calcaneofibular (CFL), posterotalofibular (PTFL) and subtalar ligament can also be injured. Most acute lateral ankle ligament injuries recover quickly with nonoperative management. The treatment program, called "functional treatment," includes application of the RICE principle (rest, ice, compression, and elevation) immediately after the injury, a short period of immobilization and protection with an elastic or inelastic tape or bandage, and early motion exercises followed by early weight bearing and neuromuscular ankle training. Proprioceptive training with a tilt board is commenced as soon as possible, usually after 3 to 4 weeks. The purpose is to improve the balance and neuromuscular control of the ankle. Sequelae after ankle ligament injuries are very common. As much as 10% to 30% of patients with a lateral ligament injury may have chronic symptoms. Symptoms usually include persistent synovitis or tendinitis, ankle stiffness, swelling, and pain, muscle weakness, and frequent giving-way. A well designed physical therapy program with peroneal strengthening and proprioceptive training, along with bracing and/or taping can alleviate instability problems in most patients. For cases of chronic instability that are refractory to bracing and external support, surgical treatment can be explored. If the chronic instability is associated with subtalar instability that is refractory to conservative measures and bracing as outlined above, surgical treatment must address the subtalar joint as well. Subtalar ligament injury and instability are probably more common than appreciated. Definition and diagnosis of this entity are difficult, however. Fortunately, it appears that in the majority of the acute injuries healing occurs with the same functional rehabilitation program as that for lateral ankle ligament sprains. For chronic subtalar instability an intial attempt at functional rehabilitation with ankle proprioceptive training and bracing should be attempted. If this program fails primary repair or reconstruction can be beneficial. Reconstructive procedures must address the subtalar joint. Subtalar instability often occurs in conjunction with talocrural instability, so careful diagnosis is critical in anyone with chronic ankle instability. If either is not addressed, the patient will continue to have problems. Deltoid ligament injuries most often occur in association with ankle fractures. They are rare as isolated injuries. If no fracture is evident on radiographs, particular attention must be paid to the syndesmosis to ensure there is not an associated syndesmosis disruption. True isolated deltoid injuries seem to do well with non-operative functional treatment as for lateral ankle ligament injuries. Deltoid ruptures associated with ankle fractures appear to heal well by addressing the other injuries and allowing the deltoid to heal on its own. It is vital to correct any syndesmosis injury and to obtain correct bony alignment. Syndesmosis injuries can be debilitating if not treated properly. Careful physical exam and interpretation of radiographs is necessary to obtain a correct diagnosis. Partial injuries appear to do well with functional rehabilitation. However, complete tears, if widening is not corrected, can lead to chronic ankle pain and early degenerative changes. Widening of the syndesmosis with a tear of the inferior tibiofibular ligaments is an indication for surgery to place a syndesmosis screw for reduction of the mortise. Protected weight bearing is required for about 6 weeks after surgery, at which time the screw should be removed. A functional rehabilitation program can then begin.