Low serotonin activity in man has been related to impulsive, self-destructive violence but not to instrumental aggression aimed at dominance. A relationship has also been suggested between aggression and high catecholaminergic activity. Several studies have reported signs of aberrant dopaminergic function in attention deficit hyperactivity disorder, autism, and schizophrenia. In 22 violent offenders undergoing pretrial forensic psychiatric investigation, interpersonal and behavioral features of psychopathy, measured by the Psychopathy Checklist Revised (PCL-R), were significantly predicted by low cerebrospinal fluid (CSF) concentrations of 5-HIAA and high CSF concentrations of HVA in multivariate regression models. CSF concentrations of MHPG did not contribute to the model. This seems to link the outward-directed aggression of psychopathy to serotonergic hypofunctioning and high dopamine turnover, which might account for disinhibition of destructive impulses.