The Ultrasound technique as an image producing procedure for fractures of the mandibular collum is outlined with physical theory and clinical examples. Advantages and disadvantages are compared and it is stated that a part of all patients with fractures might have a benefit from this method. Mentally handicapped patients, pregnant women and all sorts of fidgety patients will profit by the ultrasound investigation as the only way to ascertain the bone-fracture. There is necessity to relate the sonogram to a conventional X-ray picture whenever it is possible, for the procedure is suited to prove the fracture, not to exclude it.