Background: Internet addiction is a kind of dependence that some personality characteristics leave an important effect on using internet. On this basis, research is designed to assess the relationship between personality characteristics and internet addiction.

Materials and Method: A cross-sectional descriptive study in 1 2,480 of second and third high school students in Kashan was conducted. 400 students were selected by random cluster sampling. To measure internet addiction we u sed twenty questions to test i nternet addiction and to measure personality characteristics of students we used sixty questions questionnaire of Neo To analyze data we used Pearson correlation coefficient and regression analysis.

Results: T here is significant relationship between internet addiction with neuroticism and extroversion, but there was not any significant relationship between being conscientious with internet addiction. Conclusion : Internet addiction relates to some personality traits of students, including neuroticism and extroversion . [ZJRMS, 2012 14(1): 67-71 ]