Objective: the objective of this study is to determine the opinion of adolescents themselves about affective-sex education that they receive in order to identify the needs of these young individuals and assess the factors that prompt the incongruence between the information they receive and their behaviour regarding sex.

Material and methods: the study was carried out using a qualitative methodology, developing discussion groups with teenagers between the ages of 13 and 18 years, from the capital and province of Salamanca.

Results: adolescents believe that sex education at school could be improved  by focusing more on the practical aspects and less on reproduction, including aspects in the scope of affection and employing more real-life methods. An insufficient level of theoretical knowledge is perceived, with norms validated by the group that escape formal education, as well as a need to improve communication within the family setting.

Conclusions: it is necessary to voice out these young people´s ideas and makes the learning significant and self-guided.  It is necessary to develop a more active role in the youngsters, with special emphasis on the female gender. Sex education must be made extensive to the family setting and improved both in form and substance in the school setting. The school nurse is considered to be the most appropriate professional to develop a quality affective-sex education.