Even if risk behaviors are not limited to one period of life, adolescence has a special importance since risk behaviors to a large extent established in this period. Despite the fact that some adolescent risk behaviors can be considered to be developmentally normative and appropriate, the engagement in multiple risk behaviors during adolescence may increase the likelihood of undesirable outcomes. Various factors have been associated with adolescents' involvement in risk taking behaviors. These include parental behaviors, peer influence and adolescent risk perception. Because of their curiosity, enthusiasm and urge to try and see new phenomenon, a considerable number of youth have become addicted to alcohol, smoking cigarette, chewing "khat", dangerous medical drugs and narcotics drug. These multiple risk behavior is detrimental to many health hazards that challenge adolescents' proper physical, mental and psychological development.