Clinical findings are often insufficient to diagnose basal arachnoiditis and conventional neuroradiological techniques often fail to demonstrate the inflammatory process. Computed tomographic (CT) scans usually could demonstrate the circle of Willis, and the basilar, sylvian quadrigeminal and vermian cisterns. Cisternal anatomy could also be delineated on the CT scans by metrizamide cisternography. CT scanning may prove to be the most accurate and sensitive radiographic test for basal arachnoiditis. Findings in 8 patients were reported.