This paper deals with the ultrasonic inspection of the brain by the reflection method in order to establish the cause of displacements of the mid-line. Of 47 patients examined, 21 had displacement of the midline caused by a cerebral tumor or an intracerebral or an extracerebral hematoma. In the 2 patients, a displacement could not be established because the equipment had not been full adapted for the purpose. After some alteration, no more trouble occurred.