Introduction: One of the characteristics of modern society is the increase in sexual activity among students. The sudden increase in sexual activity among students of both sexes and the earlier age at which they enter into sexual contact exposes them to various risks, from unplanned pregnancy to sexually transmitted diseases. Aim of the study: Sexuality, with an emphasis on sexual behavior and contraception, are analyzed as the subject of the work. In this sense, the research goal of the work is to examine sexual behavior and the use of contraception among third graders. Subjects and methods: The subjects of the research are third grade students of the Pula Medical School and Pula Technical School. The main instrument of the research is the survey questionnaire "Sexual behavior". The survey questionnaire consists of two sections of questions. Socio-demographic questions, and the second section of questions refers to questions about the research topic itself. Results: The obtained results indicate that more than half of the respondents did not engage in sexual relations, and the other half who did engage in sexual relations mostly used protection during sexual relations. Statistically significant, the largest number of surveyed students have not had sexual relations so far, and of the students who have had sexual relations N=43 (41,35%), significantly the largest number have had relations more than 5 times N=31 (72,09%). Students believe that there is a 40% probability that they themselves will become infected with sexually transmitted diseases during sexual intercourse, while they attribute a significantly higher probability to infection through sexual intercourse with others. Conclusion: Third graders mostly use protection during sexual intercourse. Most third graders have had sex between one and five times by now. 3rd grade students are aware of the probability of contracting sexually transmitted diseases. Work on the prevention of sexually transmitted diseases is an important prerequisite for preserving reproductive health at an older age.