A topographic CEEG investigation was carried out in 20 drug-free, DSM-IIIR diagnosed schizophrenics and in a group of matched healthy controls. The effects of acute and chronic haloperidol treatment were then assessed in the patient group. On the baseline recording, schizophrenics showed a widespread increase in delta, theta 1 and beta 3 amplitude. Acute haloperidol administration produced a decrease in delta and an increase in slow beta amplitude. After 28 days of treatment, delta and fast beta were reduced while theta 2 and alpha 1 were increased. CEEG abnormalities in schizophrenic subjects appear, therefore, to be reduced by chronic neuroleptic treatment.