An uncontrolled clinical trial with 10 depressed patients was conducted to identify the psychopathological symptoms which may be affected by nomifensin administration, and to reveal the possible adverse effects of the drug. Consistent statistically significant improvement was noted in the course of the clinical trial on all of the assessment instruments used, and - with the exception of one patient - all improved while receiving nomifensin. Most of the therapeutic changes were seen within the first three weeks of treatment, and they included improvements of depression, as well as of hostility, a symptom which usually remains unaffeCTED BY TRICYclic antidepressant drugs. To verify the favorable therapeutic effects of nomifensin in depressed psychiatric patients, a standard-controlled clinical trial is in progress; and to verify the action mechanism of nomifensin, a study employing the probenecid technique and the measurement of spinal homovanillic acid (HVA) and 5-hydroxyindole acetic acid (5hiaa) concentration is planned.