Fourteen patients with major depression (according to the DSM-IV criteria) who were treated with paroxetine (20-50 mg) took part in the trial. We evaluated their mental status and took their digital EEG before treatment, after 14, 28 and 42 days of treatment. Frequency analysis of 120 second long periods by the use of FFT was performed. There was neither relationship between dosage of paroxetine and changes in EEG nor between score of Hamilton Depression Rating Scale and EEG changes during the performance of the trial. However we found that after 6 weeks of treatment β1 and β2 activity rose with the statistical significance. We also noticed that rising of β2 activity in the fourth week of treatment may predict a good final effect of the paroxetine therapy.