This study investigated correlations between university students' problematic internet use behaviors and shyness, narcissism, loneliness, aggression and self-perception. The participants were 424 students attending seven different faculties of a public university in Turkey; 215 were female and 209 male. Student's ages ranged between 17 and 23, with a mean of 18.69. The Problematic Internet Use Scale, Shyness Scale, Narcissistic Personality Inventory, UCLA Loneliness Scale, Aggression Questionnaire, Social Comparison Scale and a Personal Data Form were used for data collection. Correlation analysis results showed positive associations between problematic internet use and shyness and aggression. No statistically significant correlation was determined between problematic internet use and narcissism, loneliness or self-perception. The results demonstrate that individuals who are problematic users are shier and more aggressive. Shyness and aggression emerged as significant antecedent variables of problematic internet use. Suggestions are made for further studies in the light of these findings. (C) 2013 Elsevier Ltd. All rights reserved.