The aim of this study is to determine the risks of early entry into sexual relationships and the reasons why adolescents engage in risky sexual behavior. The objective of this study is also to display preventive methods that are applied to achieve responsible sexual behavior in adolescence population. The paper used methods of description and analysis of the available domestic and foreign literature and conducted researches. A review of literature and researches has found that adolescents in Croatia are poorly informed about sexually transmitted diseases and their consequences, which is particularly low on those infections that are most hazardous for them. The reason is that most of the information's adolescents receive and accept are from informal sources. Rational argument for systematic sexual education is the need to neutralize and correct false information and images about sexuality that are transmitted through the media and other informal sources.