To explore the relationship between central noradrenergic receptor responsivity and indices of impulsive aggression, growth hormone responses to infusions with the alpha 2-adrenergic receptor agonist clonidine (GH[CLON]) and responses on the Buss-Durkee Hostility Inventory (BDHI) were examined in healthy male volunteers and male patients with major affective or personality disorder. GH[CLON] values were found to correlate significantly with the BDHI "Irritability" subscale in all subjects, but especially in healthy volunteer and personality disorder patients. GH[CLON] values did not correlate with the BDHI "Assault" subscale. These results suggest a role for central alpha 2-adrenergic receptor responsivity in the personality trait characterized by behavioral irritability, but not overt assaultiveness, in humans.