A five-year-old girl of Aicardi syndrome showed moderate psychomotor retardation. She could walk and communicate. At six months of age, she developed salaam convulsion with series. Convulsions disappeared immediately after ACTH treatment. At eighteen months of age, she developed myoclonic seizures. From three years of age, head-nodding seizures with series relapsed and could not be controlled. But she could walk alone at two years old and speak a word at one and half years old. A degree of her psychomotor retardation was more slightly than others published cases of Aicardi syndrome. There were eleven reports, included our case, with mild retardation in Aicardi syndrome. The features of these are 1) late onset of seizures, 2) good response to ACTH therapy, 3) no significant abnormalities of brain except for agenesis of corpus callosum.