Myofascial pain syndrome is a common musculoskeletal pain disorder characterized by the presence of myofascial trigger points (MTrPs). The diagnosis of myofascial pain syndrome is currently made on clinical grounds. Numerous diagnostic criteria are used to identify myofascial pain syndrome, including the localization of MTrPs. Identifying the presence of MTrPs currently requires the physician to palpate the symptomatic region. Because the interrater reliability of the palpation technique has been found to be poor, numerous groups have been interested in finding objective imaging measures to localize the MTrP. This comprehensive review focuses on summarizing ultrasound imaging techniques that have shown promise in visually localizing the trigger point. The authors' literature search identified three sonographic approaches that have been used in MTrP localization: conventional gray-scale imaging, Doppler imaging, and elastographic ultrasound imaging. This review article explains the basic physics behind the imaging methods and summarizes the characteristics of the MTrP as identified by the ultrasonic techniques.