Ten cases of craniosynostosis associated with hydrocephalus were found in a retrospective review of 250 cases of children with craniosynostosis. Four children had Pfeiffer's syndrome, 3 had Crouzon's syndrome, 2 had kleeblattschädel with multiple anomalies and therefore could not be classified into a definite syndrome, and 1 had isolated sagittal synostosis. Of these 10 children, 5 had kleeblattschädel, two with Crouzon's syndrome, one with Pfeiffer's syndrome, and 2 with multiple anomalies. In all patients, hydrocephalus was controlled by a shunting procedure. Possible causes of hydrocephalus in association with craniosynostosis are discussed.