Concentrations of the major monoamine metabolites homovanillic acid (HVA) 4-hydroxy-3-methoxyphenylethylene glycol (MOPEG), and 5-hydroxyindoleacetic acid (5-HIAA) were determined in lumbar CSF of psychotic women with a schizophrenic symptomatology before and 4 weeks after treatment with sulpiride (Dogmatil 200 mg x 4). The metabolites were determined by a mass fragmentographic method. Prolactin concentrations in CSF and plasma were determined by radioimmunoassay. The clinical effects were evaluated by ratings according to the comprehensive psychopathology rating scale (CPRS) and a scale for side effects. Levels of HVA and prolactin in CSF and plasma were significantly elevated during treatment. No effects on concentrations of MOPEG or 5-HIAA were observed. The biochemical data indicate that clinical doses of sulpiride blocked dopamine receptors in the nigrostriatal pathway as well as in the tuberoinfundibular system. Treatment with sulpiride was associated with marked reductions in psychotic morbidity.