AbstractAtypical benign partial epilepsy (ABPE) of childhood is a special type of epileptic syndrome characterized by the combination of epileptic negative myoclonus, atypical absence seizures, focal motor seizures, and a continuous spike–wave during slow sleep (CSWS). Although the seizures are resistant to antiseizure drugs (ASDs) effective for focal epilepsy, they are markedly responsive to ethosuximide (ESM). An incorrect ASD choice may aggravate the seizures and CSWS, resulting in a pseudo-catastrophic state or nonconvulsive status epilepticus. In this study, we retrospectively investigated the effectiveness of steroid and ketogenic diet (KD) therapies for children with ABPE resistant to ASDs, including ESM. Adrenocorticotropic hormone (ACTH) therapy (n = 4), KD therapy (n = 4), and an oral steroid (n = 2) were tried for eight patients (two patients tried two therapies). An excellent response (seizure-free period > 1 year) was achieved by four out of four patients undergoing ACTH therapy, two out of four undergoing KD therapy, and one out of two receiving oral steroid therapy. In conclusion, steroid and KD therapies are reasonable treatment options early in the course of treatment of children with pharmacoresistant ABPE to prevent a decline in cognitive function due to the persistence of epileptic encephalopathy. The majority of patients in our case series had an excellent response, though further studies are warranted to confirm their efficacy and safety.