The diagnostic utility of different noninvasive electrode placements for deriving the electroencephalogram and detecting interictal epileptiform discharges was compared. Anterior temporal and nasopharyngeal electrodes in combination with routine scalp electrodes detected over 97% of the spikes, whereas recording from only standard electrode placements detected 58%. Minisphenoidal and surface sphenoidal electrodes were generally not helpful. In some circumstances, however, the use of surface sphenoidal electrodes provided important confirmatory information. In no case did the minisphenoidal electrodes provide unique information, and their use seems unjustified, although the inclusion of other nonstandard electrodes in the recording montage is important to increase the yield.