RESUMEN
The objectives of this study were to determine the frequency of risk behaviors in high school students. In this cross sectional study 2400 high school students in urban areas of Tehran were selected by multy stage sampling. They filled in a questionnire in clasroom. Then, data were analysed in a descriptive function. Frequency of health risk behaviors were intentional injuryis [41.5%], unintentional injuryis [88.7%], smoking cigarette [8.7%], alcohol drinking during the 30 days preceding survey [7.4%], other drug abuse [2.7%], sexual intercourse during life [20.2%], unhealthy dietery behaviors [14.7%] and physical inactivity during 7 days preeceding the survery [32.6%]. Sex differences were detected in health-risk behaviors. In high school students frequency of health-related risk behaviors were high. School personnel should work with community leaders and health care professionals to provide educational materials for students and their parents. Collaboration of school personnel and health care provider, as a team can develop the knowledge and skill necessery to help students make healthier choices