Hemispherectomy (more recently referred to as hemispherotomy or callosotomy) is a complex surgical technique designed to disconnect one cerebral hemisphere from the other. Hemispherectomy has been used as a surgical technique since the early twentieth century, when Dr. Walter Dandy removed gliomas from five patients in 1928 with relative success. Contemporary hemispherectomy procedures are modified versions of Rasmussen's functional hemispherectomy designed to minimize the amount of excised brain matter and postoperative complications. Hemispherectomy is considered a sensitive surgical procedure due to associated postoperative complications, such as hydrocephalus. Neuroimaging plays a vital role in the initial diagnosis and follow-up of various neurodegenerative consequences that may require hemispherectomy. Modern neuroimaging techniques include structural and functional magnetic resonance imaging (MRI), computerized axial tomography (CAT or CT), photon emission tomography (PET), and single photon emission computed tomography (SPECT). Hemispherectomy has become an established surgical treatment for carefully selected pediatric patients who suffer from intractable and pharmacologically resistant epilepsy.