Alteration in the cerebrospinal fluid (CSF) circulation was studied in 62 patients with neurosurgical diseases by CT cisternography using a water-soluble contrast medium, metrizamide, and also with radionuclide (169Yb- or 111In-DTPA) cisternography. As a rule, the patterns of both methods were in good agreement. The findings were classified into 3 types and 5 subdivisions. CT cisternography is useful for sequential observation of the CSF circulation with detailed morphological definition, and radionuclide cisternography is useful for observing the general flow of CSF. Some patients with hydrocephalus showed hypodensity around the ventricle, where migration of metrizamide was observed on CT images after its ventricular reflux. This suggests an increased transependymal resorption of CSF. The mathematical analysis of attenuation coefficients on CT cisternography provided more objective and quantitative data for study of CSF dynamics.