This study aims at scrutinizing the action of Behavior-Brain systems in patients with obsessive-compulsive disorder and patients with Phobia by comparing them. The study is based on Jeffry Gary personality Theory.

20 patients with obsessive-compulsive disorder and 20 patients with Phobia that matched together by age, education level and gender were selected from patients referred to consulting clinics in Ardebil in 2008. Gary & Wilson personality questionnaire administered for assessing the Behavior-Brain systems action. The collected data were analyzed using descriptive and independent T-test to test the hypothesis generated in the study.

Analyzing the collected data shows that there is no significant difference between Phobic and obsessive patients in behavior activating systems and behavior inhabitation systems; but there is significant difference between two groups in fight -flight system.

The results of this study are in agreement with basic hypothesis of Gary's Reinforcement Sensitivity Theory and neuro-psychological status of patients with disorders. The reason of no significant difference between two behavior activating systems and behavior inhabitation systems in phobic and obsessive patients might be due to the similarity of behavior roots in these two disorders.