A multi-lead C-EEG investigation was carried out, in order to evaluate changes induced by acute and chronic treatment with haloperidol in DSM-III-R schizophrenics. After the acute treatment the main C-EEG changes were (1) a significant decrease of delta relative power (RP) over all the explored leads and of theta 1 over the occipital leads; (2) an increase in alpha 2 and beta 2 RP, as well as a decrease of beta 3 RP confined to the anterior temporal leads (T3, T4). During chronic treatment, C-EEG changes observed were (1) a significant decrease of delta RP and an increase of theta 1 RP; (2) an increase of alpha 1 and alpha 2 RP; (3) a significant decrease of beta 1, beta 2 and beta 3.