In recent years ultrasonography (US) has emerged as the imaging technique of choice for guiding diagnostic and therapeutic procedures including those related to the musculoskeletal system. However, the absence of ionizing radiation and the elevated safety of the method must not lead us to forget that there are precautions and contraindications to keep in mind, which are crucial to the protection of both the patient and the physician.Among these precautions it is first of all essential to obtain the patient's accurate clinical history including current medication, particularly if it involves drugs influencing the blood clotting, and information related to possible allergies. The patient should furthermore receive detailed information concerning the procedure (sterile precautions as well as possible side-effects of the drugs which will be injected). In addition to this, there must be a close contact between the radiologist and the patient's general physician (GP) in order to obtain the best possible result of the procedure.