Introduction. Reflex epileptic seizures are caused by a specific sensorial stimulus which determines their classification. Photosensitive epilepsies are the commonest forms and are included with the idiopathic generalized epilepsies. Development and conclusions. We analyze the different responses to intermittent light stimulation, in both normal and epileptic persons. and study the various epileptic syndromes in which photosensitivity is seen. The purely photosensitive (photogenic) epilepsies are characterized by seizures caused only by light as compared with the epilepsies with photosensitivity which also present spontaneous seizures. Special mention is made of seizures induced by the television screen, computer screen and video-games. The palpebral myoclonias with absences may be considered to be reflex seizures, since they are induced by eyelid closure, and include the vary rare self-induced epileptic seizures. Finally we study the epileptic seizures induced by 'pattern' and exclusively due to intermittent light stimulation.