PURPOSE: The purpose of this study was to evaluate the usefulness of computed tomography(CT) and magnetic resonance imaging(MRI) in experimental bacterial meningitis. MATERIALS AND METHODS: CT and MR images of experimental bacterial meningitis were obtained after inoculation of 1ml suspension of 106/ml Staphylococcusaureus directly into the supratentorial arachnoid space of 18 New Zealand white rabbits. Each animal was studied with both Pre-enhanced and post-enhanced CT and MRI at 12, 24, 48 hours and 1 week. Cerebrospinal fluid of all of18 rabbits were sampled and cultured for bacterial growth. RESULTS: All of 18 rabbits had the clinical symptoms such as neck stiffness and anorexia within 24 hours after the inoculation. Cerebrospinal fluid cultures werepositive for Staphylococcus sureus growth. Gd-enhanced MRI exhibited diffuse enhancement along the thickened supratentorial meninges earlier than CT. in Gd-enhanced MRI, the mean contrast enhancement ratio(CER) at supratentorial meninges increased to 1.93 at 12 hours and 2.99 at 24 hours from 1.06 at 0 hour. Histologic evaluation demonstrated inflammatory cell infiltration into the meninges. MRI also identified the complications of mening it is such as ependymitis and hydrocephalus more effectively than CT. CONCLUSION: These results indicatedthat Gd-enhanced MRI detected earlier the abnormal findings of bacterial meningitis and evaluated more effectively the complications of mening it is compared with CT. MRI was more useful than CT in evaluation of the bacterial meningitis.