The efficacy of epilepsy surgery depends on whether the epileptogenic zone is completely removed. Therefore, the accurate localization of the epileptogenic zone becomes a critical issue. The localization of the epileptogenic zone currently relies on a combination of diagnostic tools for assessment. These include epilepsy history, symptomatic features of seizures, neuropsychological examination, general scalp EEG, audio-visual EEG, magnetic resonance imaging (MRI), functional MRI, PET, SPECT, and magnetoencephalography. Invasive EEG, including intraoperative cortical EEG and long-range monitoring with intracranial buried electrodes, is also performed when necessary. The reason why so many examination methods are required is that no single method can determine the location of the epileptogenic zone with 100% certainty. The accuracy of the diagnosis of the localization of the epileptogenic zone is significantly improved by the combined application of multiple examination methods.