For specific indications, ultrasound (US) is an efficient and inexpensive alternative to magnetic resonance (MR) imaging for evaluation of the ankle. In addition to the tendons and tendon sheaths, other ankle structures demonstrated with US include the anterior joint space, retrocalcaneal bursa, ligaments, and plantar fascia. Ankle US allows detection of tenosynovitis and tendinitis, as well as partial and complete tendon tears. Joint effusions, intraarticular bodies, ganglion cysts, ligamentous tears, and plantar fasciitis can also be diagnosed. As pressure for cost containment continues, demand for US of the ankle may increase given its lower cost compared with that of MR imaging. In most cases, a focused ankle US examination can be performed more rapidly and efficiently than MR imaging. Familiarity with the technique of ankle US, normal US anatomy, and the US appearances of pathologic conditions will establish the role of US as an effective method of imaging the ankle.