Gray offered a biological model of personality consisting of three brain-behavior systems based on individual differences. These three systems provoke different reactions like fear, anxiety and so on. The aim of this investigation was to examine the differences of the pattern of activities in the addicts and non-addicts. In so doing, a group of 96 addicted subjects (48 men and 48 women) were matched with a group of 96 non-addicted one (48 men and 48 women) and Gray-Wilson Personality Questionnaire was administered to them. The results of the study demonstrated that both male and female addicts had higher scores in Behavioral Activation System (BAS), in comparison with non-addicts. In addition, no significant difference could be detected between Behavior Inhibition System (BIS) and Fight- Flight System (FFD) scores of the groups. Finally, the results of the study confirmed the hypothesis that addicts possess the hyperactivity of BIS