1. Attention is called to a roentgenographic syndrome of hemilateral cerebral hypoplasia and atrophy with concomitant increase of thickness of the skull and enlargement of the head sinuses which occurs in certain convulsive states.2. Nine cases are described which presented this syndrome. The etiological factors were traumatic, inflammatory or vascular.3. The nature of the pathological process is discussed from the point of view of brain growth.