Ultrasound examinations (US) of the brain are possible in the presence of an acoustic window in the skull, either after craniotomy or through an open fontanelle. In this study 19 children were examined, 11 via a suboccipital craniectomy; 9 cases were examined more than once. Via this suboccipital route most of the contents of the posterior fossa, the third and lateral ventricles could be made visible. In two patients with a temporal or parietal craniotomy the involved hemisphere could be visualized. Six patients were examined via the open fontanelle after insertion of a ventriculoperitoneal shunt (VPS). In three of these cases the examination was undertaken to evaluate also a posterior fossa cyst. The findings were compared with CT if the findings were equivocal.