Magnetoencephalography (MEG) has a long history of development for the application of epilepsy. Technical and clinical validation of spike source estimation has been demonstrated in most partial epilepsies. The question that needs to be clarified concerns clinical value: Do identification and localization of epileptiform discharges play an important role in the determination of epilepsy localization for surgery? EEG is the mainstay in the investigation of seizure disorders and will remain so because it alone possesses the attribute of long-term recordings that can capture seizures. In contrast, MEG has the unique capability of nearly instantaneous high-resolution recording, with detection sensitivity and spike localization precision beyond that of EEG. Do these distinctions matter from a clinical standpoint?