A review of a large series of patients treated surgically for hydrocephalus yielded a group of 7 children with generalized thickening of the calvaria (averaging 2.5 times normal for age and sex) and premature fusion of the cranial sutures of a varying extent. The reasons why these few patients (out of a much larger post-shunt group not so affected) show the changes described is unknown, although some parallels with findings from animal studies can be drawn. The clinical significance of this syndrome appears to derive primarily from the premature sutural fusion, which may impede brain growth and render the child more dependent upon the proper function of his shunt tube for maintenance of normal intracranial pressure.