We investigated the laminar profile of visually evoked paroxysmal discharge following bicuculline administration in area 17 of the alert macaque. Paroxysmal discharge was focussed in lamina 3, with lesser concomitants in infragranular laminae. There were no marked effects on the flash-evoked laminar activation sequence. The neocortex of the alert macaque studied with the present techniques may provide a model for evaluating basic mechanisms of epilepsy, and for linking these to the macroscopic phenomena seen in humans.