Introduction: There were many conflicts about involvement of Internet addiction in fifth version of Diagnostic and Statistical Manual of mental disorders (DSM-V). As personality characteristics are one of the risk factors of risky behaviors, this study have investigated the role of neurobehavioral factors of personality in Internet addiction.

Materials & Methods: This study is a correlational study. For this procedure, among all students of Kharazmi university of Tehran, 359 participants (196 male and 163 female) were selected through Multi-stage cluster sampling. They answered Jackson-5 scale and Young’s Internet addiction test. Data were analyzed by stepwise regression method by SPSS.22.

Findings: Analyzing data showed that Freeze and Fight of Fight/Flight/Freeze system could predict Internet addiction (P<0.001, R= 0.40, R²= 0.16). After analyzing genders separately, Freeze, Flight, and Fight could predict addiction in males (P<0.001, R= 0.55, R²= 0.30), but only Fight and Freeze predicted addiction in females (P<0.001, R= 0.26, R²= 0.07).

Discussion & Conclusions: From all brain-behavioral systems, only fear and sensitivity to threatening stimuli affects Internet addiction. This imply that Internet addiction is somehow different from other risky behaviors; therefore, to prevent and treat Internet addiction, sensitivity to punishment and fear should be considered more important than sensitivity to reward.