Infantile spasms (IS) are seizures associated with a severe infantile epileptic encephalopathy. Both cessation of spasms and electrographic response are necessary for the best neurodevelopmental outcomes. Adrenocorticotrophic hormone (ACTH), or prednisolone, or vigabatrin are considered the first-line treatment individually. However, ACTH expense and availability are the barriers in developing countries including Thailand. Vigabatrin, therefore, is the first recommended by Epilepsy Society of Thailand due to ACTH unavailability. Recently, combined steroid treatments (either ACTH or high dose prednisolone) with vigabatrin are superior in cessation of spasms compared to steroid treatment alone. Thus, this study is aimed to compare the efficacy of vigabatrin with high dose prednisolone combination therapy and vigabatrin alone.