The aim of the present study was to assess androgen plasma levels and biogenic amine metabolites in a sex-offender group as well as to investigate the relationship between the biological findings and the impulsive, aggressive, and suicidal profile of the offenders. Fifty-seven males convicted for rape and 25 normal males comprised the study sample. We found that although both testosterone levels and aggression-impulsivity scores were higher in the group of rapists, testosterone levels were not associated with the aggression and impulsivity scores. Nevertheless, aggression-impulsivity scores were clearly associated with luteinizing hormone levels. This association may indicate a hyperactive hypothalamic-pituitary-gonadal axis, possibly the result of a reduced serotonergic activity.