HHE syndrome is characterized by hemiconvulsive seizure, hemiplegia and epilepsy occurring in sequence. Recently, cytotoxic edematous swelling of one hemisphere was presented as the pathogenesis because high signal intensity was shown in the diffusion image but no remarkable findings were noticed in the FLAIR image and T2WI in two cases presented by Freeman etc. The clinical course and the radiologic findings in our patient was the same as the above description other than sparing paracentral lobule. This reinforces the assumption that the brain damage in HHE syndrome is not induced by vascular hypoxic damage but by selectively cytotoxic damage through immunologic pathogenesis. Therefore, diffusion image is needed for the diagnosis of HHE syndrome in a febrile convulsive child. Also, early adequate treatment is required such as immunosuppressive treatment with high dose steroid and intravenous immunoglobulin. Furthermore, a proper measure to reduce cerebral edema is essential for the prevention of neurologic sequalae and deterioration to epilepsy.