MRI findings of a 14-year-old boy with subdural empyema (SE) are reported and compared with those of serial CT-scan. He was admitted with fever, headache, right hemiplegia and facial palsy. Initial enhanced CT-scan revealed a slit left lateral ventricle and a shift in the mid-line structures, but failed to detect any SE. MRI at 10 days after admission clearly demonstrated SE as an area of low intensity on T1-weight (T1WI) and very high intensity on T2-weight (T2WI). Post-contrast enhanced MRI (CE-MRI), using Gd-DTPA, showed a contrast enhancement in the wall of SE. However, no definite parenchymal abnormal intensity areas were detected, suggesting that the diagnosis was made sufficiently early for timely treatment and good neurological outcome. CE-MRI proved to be a more powerful and better diagnostic procedure than enhanced CT-scan, and was very useful in determining the state and development of the disease.