Twenty supratentorial and 10 infratentorial arachnoid cysts are reported. The patients were from 0 to 15 years of age. The commonest presenting symptoms in children were cranial enlargement, epileptic seizures, and psychomotor retardation. Neuroradiological evaluation included CT, metrizamide CT, cisternography, and angiography. Echography was performed in 5 newborns. Therapeutic criteria according to the clinical and neuroradiological findings are reviewed. Cystoperitoneal shunting in combination with ventriculoperitoneal shunting for associated hydrocephalus is considered the treatment of choice. © 1987 Springer-Verlag.