Development of computerized tomography (CT) has greatly improved the ease and accuracy of identification of fluid-containing intracranial cavities. CT reveals the size, location of the cyst, associated brain disorders and relationship between the cyst and the subarachnoid space or the ventricular system. An accurate diagnosis by plain CT is sometimes difficult to obtain. It is important to determine whether the cysts communicate with the ventricular system or subarachnoid space for the selection of the surgical treatment. The cerebrospinal fluid dynamics was examined by CT cisternography and CT ventriculography using metrizamide injected into lumbar subarachnoid space or ventricular system in 27 children of intracranial cystic lesion during the last two years. Serial CT scanning and analysis of the CT number in the cystic cavity was performed according to the necessity. The preoperative knowledge of the location of the cysts and the CSF dynamics has been proved to be useful for the surgical treatment. CT cisternography and CT ventriculography would be regarded to be safe and reliable neuroradiological examinations in evaluating the CSF dynamics of the intracranial cystic lesion of children.