Adolescence is a time of significant change for human beings, bringing new forms of social interaction and exposure to risks. At this stage, concerns arise around early pregnancy and sexually transmitted infections (STIs), which are considered public health problems and are directly related to low adherence to condom use. The objective was to analyze the level of knowledge of adolescents about STIs and contraceptive methods. This is a descriptive-exploratory research of a quantitative nature, carried out with students between 14 and 15 years old, from two educational institutions, public and private, through the application of printed questionnaires and via the Google Forms platform, on the knowledge of contraceptive methods and STI prevention. Regarding the results, 98 students were interviewed, 44 from the Public School (GEP) and 54 from the Private College (GCP). The female audience gained prominence in both schools, totaling 54 students. The prevalent age in both groups was 14 and 15 years. With regard to knowledge about STIs and contraceptive methods, in both samples the adolescents were aware of and had been instructed about STIs. Regarding contraceptive methods, 38 (86.4%) were instructed in the GEP and 54 (100%) in the GCP. In the case of contraceptive methods, in both groups as a whole, they know the male condom, however, in the GEP 6 (13.6%) know about coitus interruptus, in the GCP, in turn, only 15 (27.8% ) know the vaginal ring. GCP adolescents are more aware of contraceptive methods than GEP. Given the above, it is possible to understand that the knowledge presented by the students on the subject is ineffective in both schools, and it is essential to expand the activities proposed by the schools, since the students themselves consider them necessary for a better understanding of issues involving sexuality.