Background: The new phenomenon of Internet addiction among teenagers and young adults is one of the modern addictions in industrial and post-industrial societies. The purpose of this research was to predict the Internet addiction based on the personality characteristics of high school students in Kerman. Methods: This research was a descriptive correlational study. The statistical population included 538 male and female students in the second grade of high school in Kerman during 2010. The subjects were randomly selected by multistage clustering. Data was collected by two questionnaires including the five-factor Revised NEO Personality Inventory and the Internet dependency questionnaire. The data was analyzed using ANOVA test and multivariable regression analysis. Findings: The findings showed a significant relationship between the personality trait of emotional stability and academic fields, i.e. students with higher emotional stability experience less negative emotions when confronting with problems. Therefore, it is less likely for them to alleviate the negative emotions by the extreme and obsessed usage of the Internet. In addition, it appears that the students with high extroversion scores prefer social, face to face interactions with other people to interaction with the virtual world. Conversely, more introvert students avoid interactions with other people due to their shyness. Thus, they communicate with the virtual world more. Conclusion: Three personality traits of loyalty, emotional stability, and extroversion are the most significant predictors of Internet addiction in high school students. Keywords: Internet addiction, Characteristics of personality, Students, Kerman.