Instability of the subtalar joint can follow inversion stress injuries to the lateral ankle and hindfoot. Ligaments involved in the injury include the calcaneofibular, lateral talocalcaneal, cervical, interosseous talocalcaneal, or a combination. Although the problem most often occurs in conjunction with lateral ankle instability, it may be an isolated problem and it is not corrected equally well by the various lateral ankle ligament reconstructions. Techniques available for diagnosis include routine stress radiographs of the ankle, which also include the subtalar joint, specific subtalar stress radiographs, stress tomograms, fluoroscopy, or subtalar arthrograms. Once diagnosed, subtalar instability symptoms can be treated by either nonoperative or operative means.