The magnetic resonance imaging (MRI) findings in 14 patients with biopsy or polymerase chain reaction proven herpes simplex encephalitis were retrospectively reviewed to evaluate the diagnostic value of MRI in the early diagnosis of herpes simplex encephalitis in children. In addition to the early findings, follow-up MRI scans were obtained in four patients. Typical limbic system involvement was seen in 78 percent of the cases. Contrast-enhanced MRI was found to be superior to routine MRI sequences and computerized tomography (CT) in the early detection of inflammation. Follow-up MR images in four patients demonstrated the volume loss and late petechial hemorrhage in the involved regions. Magnetic resonance imaging is the method of choice in the diagnosis and follow-up of herpes simplex encephalitis.