SYNOPSISThe typical lateralization of pain and autonomic dysfunction in Cluster Headache has prompted severalresearches, seeking a pathogenetic interpretation of this syndrome, considering this peculiar clinical aspect.In this study, we evaluated VEPs responses in 20 CH subjects, 10 with right-sided pain and 10 with left-sided pain,comparing them with 20 VEPs responses in normal subjects. VEPs morphologies and latencies did not differ fromnormal controls. On the other hand, P100 amplitudes are significantly lower than controls, on the pain side only.This asymmetry of the response is constant and exceeds normal variation. These data suggest a centralinvolvement in CH pathogenesis. The possible mechanisms of this involvement are discussed.