This research aims to define adolescents' general Internet usage and online gaming behaviors and to investigate their problematic Internet usage levels in terms of these behaviors. Moreover, the research intends to examine the relationships among duration of general Internet usage, duration of online gaming, problematic Internet usage levels, and procrastination, as well as qualitatively define adolescents' opinions about the Internet. In the research, the study group consists of 1,088 high-school students. Data was collected by means of the Problematic Internet Usage Scale-Adolescent, General Procrastination Scale, Academic Procrastination Scale, and Personal Information Questionnaire. According to the research results, adolescents' average duration of daily Internet usage is 3.42 hours and the longer the Internet is used for, the higher their levels of problematic Internet usage. Adolescents use the Internet most commonly on their cellphones, and cellphone users have higher problematic Internet usage levels. Adolescents use the Internet mainly "to have fun -pass time," and those who use the Internet for these purposes have higher problematic Internet usage levels. A low-level and positively significant relationship exists for problematic Internet usage levels with general procrastination and academic procrastination. Furthermore, adolescents mostly see the Internet as " a tool for obtaining information".They mostly state the Internet's positive effect as " Internet lets me obtain information" and its negative effect as " causing me to waste time".