This is a descriptive study conducted to examine problematic internet use in terms of gender, social anxiety and peer relations. The sample is comprised of a total of 682 students high school students (356 female (52,2%) and 326 male (47,8%) studying at the 9th, 10th, and 11th grades during the Fall semester of the 2012-2013 Academic Year in three different high schools in cankaya, Etimesgut, and Mamak districts of Ankara. In order to determine students' problematic internet use, `Problematic Internet Use Scale-Adolescent' developed by Ceyhan and Ceyhan (2009), to determine their social anxiety levels, `Social Anxiety Scale for Adolescents' developed by Aydin and Tekinsav-Sutcu (2007) and adapted to high school students by the researchers, and to determine their peer relations, 'Peer Relations Scale' developed by Kaner (2002). In the study, t-test and hierarchical regression analysis were used to analyze the data. The result of the study showed that male high school students have a higher level of problematic internet use compared to female high school students. Hierarchical regression analysis results, explained that fear of negative evaluation sub-dimension of social anxiety and social avoidance and nervousness in general situations have an important effect (22%) on problematic internet use; moreover, it was also determined that opening oneself sub-dimension of the peer relations variable and loyalty variable meaningfully contribute (%6) to this.