47’, XYYs represent a high percentage of patients admitted in security settings for aggressiveness. By using a polygraphic technique and amine metabolite estimation in the cerebrospinal fluid (CSF), an attempt was made to evaluate the functional activity of the central aminergic system of these patients. No drastic change was observed in sleep patterns of XYYs. The estimation of CSF amine metabolites revealed a normal value for homovanillic acid, but a significant decrease of 5-hydroxyindoleacetic acid turnove