Levetiracetam is one of the new anticonvulsant drugs that has a high therapeutic index and potential antiepileptogenic effects. Herein, we report a patient with multidrug refractory epilepsy and Ohtahara syndrome who was accidentally administered 300 mg/kg/d for 35 days by her mother. To our knowledge, there are only a few cases of accidental overdose of levetiracetam in pediatric patients reported in the literature, and this case study is the first to report such a high and long-term dose in an infant who showed no adverse effects.