In recent years, musculoskeletal ultrasound (MSUS) has achieved an important role not only in clinical applications (for diagnosis and management of various musculoskeletal disorders), but also in research, due to its several advantages (being convenient, inexpensive, non-invasive, repeatable, providing high-resolution dynamic and comparative imaging, and not requiring any exposure to radiation). As such, MSUS has increasingly become a valuable tool in the daily clinical practice of Physical and Rehabilitation Medicine (PRM) physicians and, where used in a rehabilitation setting, it can significantly contribute to the diagnostic and therapeutic algorithm of rehabilitation patients. For these reasons, the MSUS probe can be now thought of as synonymous with the physician's stethoscope. Additionally, scanning is quite comfortable, and sometimes even more reassuring for the patient than the physician: seeing is believing . In this book, aside from drawing attention to the growing issues in the agenda of PRM physicians using MSUS, the authors also discuss basic technical features of the technique, and focus on the both diagnostic and interventional utility of MSUS in different health conditions involving muscles, tendons, ligaments, nerves, and joint lesions. Potential readers: orthopedic specialists, rehabilitation specialists, rheumatologists, physiatrists, physiotherapists, sonographers.