Oral dexamethasone was administered at a dose of 0.075 mg/kg/day for a boy with ataxia‐telangiectasia. The SARA score was improved by 7.0 points after dexamethasone treatment over a period of 28 days. The body weight was increased by 1.4 kg after 4 weeks leading to dose titration to 0.05 mg/kg/day.