To test the hypothesis that traits of aggression and impulsivity correlate negatively with central serotonergic system function in a nonpatient population, a standard fenfluramine challenge (for assessment of serotonergic responsivity) and behavioral measurements germane to aggression/impulsivity were administered to a community-derived sample of 119 men and women. In men, peak prolactin responses to fenfluramine correlated significantly with an interview-assessed life history of aggression (r = -.40, p < .002), the Barratt Impulsiveness Scale (r = -.30, p < .03), and traits of Conscientiousness (r = +.30, p < .03), Neuroticism (r = -.31, p < .02) and Angry Hostility (r = -.35, p < .01) on the NEO-Personality Inventory. No significant relationships were observed across all women, although subanalyses restricted to postmenopausal subjects (in whom ovarian influences on prolactin secretion may be mitigated because of diminished estrogen) showed a pattern of behavioral associations somewhat similar to that seen in men. By extending documented relationships between an index of central serotonergic system function and traits of aggression and impulsivity to a more normative range of population variability than is represented in prior literature, this study supports speculation that these associations reflect a basic neurobehavioral dimension of individual differences.