Forty adolescents and adults who exhibited aggressive behavior within the six months prior to evaluation by physically attacking another person or destroying property were evaluated with brain SPECT imaging. A control group of 40 psychiatric patients who had never been reported to exhibit aggressive behavior were also studied. The brain SPECT studies were read blind to aggressiveness by nuclear physician on two separate occasions. The interreading reliability was very high. The brain SPECT patterns of the group with aggressive behavior showed significant differences from the control group in several areas of brain. These findings were most often seen in the following combination: decreased activity in the prefrontal cortex, increased activity in the anteromedial portions of the frontal lobes, leftsided increased activity in the basal ganglia and/or limbic system in comparison to the whole brain and focal abnormalities in the left temporal lobe. These findings indicate a possible cerebral perfusion profile for those who exhibit violent or aggressive behavior. Several case studies and the implications for treatment are discussed.