The effects of intermittent light stimulation on chickens genetically predisposed to generalized convulsions are described. Epileptic chickens (homozygous recessive) convulse when exposed to intermittent light stimulation at 10–25 flashes per second, whereas normal (homozygous dominant) and carrier (heterozygous) hatch mates are not affected. The resting electroencephalogram (EEG) of epileptic chickens is markedly different from that of their nonconvulsive hatch mates, being characterized by high-amplitude slow waves with periodic spikes and spike–wave complexes. Prior to the onset of light-induced seizures, high-voltage spikes, at the same frequency as the stimulus, appear in all leads of the epileptic EEG. For a short time after a convulsion the EEG of epileptic chickens remains flattened, suggesting decreased electrical activity similar to the postictal depression seen in the EEG of human epileptics.