Objectives. - This study aimed to explore the relationship between online game addiction and aggression, self-control, and narcissistic personality traits, which are known as the psychological characteristics linked to "at-risk" populations for online game addiction. Method. - A total of 1471 online game users (males 82.7%, females 17.3%, mean age 21.30 +/- 4.96) participated in this study and were asked to complete several self-report measures using an online response method. Questionnaires included demographic information and game use-related characteristics of the samples, the online game addiction scale (modified from Young's Internet addiction scale), the Buss-Perry aggression questionnaire, a self-control scale, and the narcissistic personality disorder scale. Results. - Our results indicated that aggression and narcissistic personality traits are positively correlated with online game addiction, whereas self-control is negatively correlated with online game addiction (p < 0.001). In addition, a multiple regression analysis revealed that the extent of online game addiction could be predicted based on the person's narcissistic personality traits, aggression, self-control, interpersonal relationship, and occupation. However, only 20% of the variance in behavioral consequences was explained with the model. Conclusion. - An interesting profile has emerged from the results of this study, suggesting that certain psychological characteristics such as aggression, self-control, and narcissistic personality traits may predispose some individuals to become addicted to online games. This result will deepen our understanding of the "at-risk" population for online game addiction and provide basic information that can contribute to developing a prevention program for people who are addicted to online games. (C) 2007 Elsevier Masson SAS. All rights reserved.