Aim: The aim of this cross-sectional study was to determine the prevalence of the self reported health behaviors and differences in these behaviors by gender and grades in high school adolescents in İzmir, Turkey.Material and Methods: A stratified cluster sampling procedure was used for this cross-sectional study. The study sample included 2 296 students attending 22 high schools in Izmir. As a data collection instrument, some questions from the Health Behavior in School-aged Children Study 2009/2010 questionnnaire and questions which were developed by the researchers to understand behaviors of internet use in adolescents were used. Chi-square tests and Cramer's V statistics were used for statistical analyses. Results: Among the high school students, 33.8% experimented smoking, 26.3% smoked cigarette during the 30 days before the survey, 14.9% smoked cigarette regularly during the 30 days before the survey, 54.1% experimented drinking alcohol, 38.4% drunk alcohol during the 30 days before the survey, 31.6% got drunk, 10.9% were adequately physically active, 59.9% watched TV for a long period of time, 72.8% used internet for a long period of time, 48.1% ate breakfast regularly, 36.2% ate adequate amount of fruit, 14.1% ate adequate amount of vegetable, 31.3% ate candies and chocolate very often, 18% drunk soft drink very often, 30.3% were bullied, 29.9% bullied others and 41% involved in a physical fight.Conclusions: These results showed that "Adolescent friendly health services" should be generalized all over Turkey, physicians should evaluate each adolescent for his/her health behaviors in each visit and implementation of prevention programs which adopt a health promotion perspective is necessary begining from the elementary school