This investigation has been directed to estimate to what extent a GABA derivative, beta-(p-chlorophenyl)-gamma-aminobutyric acid (baclofen), is active at the cortical and subcortical level. Selected nonpsychotic patients with slight depression symptoms were given 30 mg of baclofen daily for a period of 3–5 weeks. Brief Psychiatric Rating Scale and Standardized Hamilton Interview for Depression were used for clinical evaluation. EEGs were recorded prior to and at different times during treatment. An automatic analysis completed by multivariant statistics of EEG spectral values was performed. EEG changes were characterized by a significant increase of slow waves and decrease of fast activity. These results can support the view that baclofen is effective even at the highest levels of the central nervous system.