The patellar tendon is well suited to sonographic evaluation because it is large and superficial and thus easily demonstrated. Sonography is a focused examination, concentrating on the area of pain and clinical suspicion. Its advantages over MR imaging are the speed of performance, better spatial resolution, capability of dynamic evaluation, and real-time guidance for percutaneous procedures. In addition, the advent of extended field-of-view imaging allows the demonstration of the entire length or cross section of an area of interest, matching MR imaging's ability to display a large anatomical region. This article reviews the sonographic appearances of disorders of the patellar tendon.