Twenty drivers were remanded to our treatment program by the courts following arrests related to serious aggressive driving behaviors. Ten additional drivers entered our program in response to our advertisements thus identifying themselves as aggressive drivers. Psychophysiological assessments were conducted on all 30 drivers and heart rate (HR), systolic and diastolic blood pressure (SBP and DBP), and skin resistance level (SRL) were measured in response to exposure to a mental arithmetic neutral stressor, two idiosyncratic, audio-taped, aggressive driving vignettes (audio 1 and audio 2), and one non-driving related fearful vignette. Fourteen non-aggressive driving controls also completed the assessment. The results indicated that the aggressive drivers (ADs) showed significantly more SBP responsivity during audio 1 and audio 2 and significantly less SBP reactivity during the mental arithmetic stressor than the controls. The aggressive drivers then completed a four-week, group intervention which included relaxation techniques specifically targeting aggressive driving behaviors. The same psychophysiological assessment was conducted at post-treatment. The results showed significant pre- to post-treatment decreases in HR, p<0.003, SBP, p<0.01, and DBP, p<0.02 during audio 1. Similarly, decreases were evident in audio 2 in SBP, p<0.03 only. No decreases in reactivity occurred during the neutral stressor or fearful situation.