Evidence is growing that aggressive behavior and impulsivity have subgroups. The subscales of the Urgency, Premeditation, Perseverance and Sensation seeking (UPPS) impulsivity scale and the Bryant and Smith shortened and refined version of the Aggression Questionnaire were used to describe and compare impulsive and aggressive behavior in extremely violent and aggressive male inmates and non-violent healthy male controls. The Mann-Whitney test showed that there was a significant difference (p < 0. 006) in the total UPPS impulsivity scale scores between the aggressive inmates and the controls. The subscales revealed that this difference was based mainly on the urgency score (p < 0. 003). On the aggression subscales, the inmates scored significantly higher for physical aggression than the controls (p < 0.001), but no significant difference was seen between inmates and controls for verbal aggression, anger and hostility, although the exact pvalue was very close to statistical significance at 0.054. Regression analysis revealed a strong relationship between urgency and the aggression subscales hostility (p = 0.0004) and anger (p = 0.003) and that urgency was also linked to symptoms of anxiety (p = 0.008). Finally, a statistically significant link was found between both hostility (p = 0.0003) and anger (p = 0.002) and symptoms of anxiety. The highly selected subgroup of extremely violent criminals in this study were more physically aggressive than non-violent controls, with urgency as the driving feature in their impulsive behavior, and hostility, anger and symptoms of anxiety as underlying traits.