The purpose of this study was to gain the basic information on the program necessary to conduct a sex education for the adolescents. The subjects of the study were 435 males and females, middle and high school students in Chonbuk, Korea. The results showed that the most serious problems of the adolescents` knowledge regarding sex were as follows; 1) Acquistition of a sex knowledge in the informal realm, 2) Confusion of perception regarding sex or sense of value, 3) Excess exposure to harmful circumstances. Lastly, perception regarding sex of adolesecents was dependent on school grade, which was one of the individual background variables. And experience of sexual harassment was dependent on parents` relationship, which was one of the individual background variables. To establish a healthy sex culture, systematic sex education has to be conducted in the formal realm.