ABSTRACT. Aim: Sexually transmitted diseases (STD), unexpected pregnancies and sexual abuse have become an inevitable global public healthcare problem. Due to the constant increase in the number of STD cases, the prevention of these diseases is the basic prerequisite for reproductive health in the adult age. The aim of the study was to evaluate certain aspects of sexual behaviour in the 16 year old age group. Methods: The survey was conducted among 595 second grade students in 4 secondary schools in the year 2007 by means of valid self-reported questionnaires. Results: Sexual experience was reported by 26,6% of girls and 33,4% of boys. The majority of this study group had their first sexual intercourse at the age of 16. Girls reported sexual experience with older partner more often (63%) than boys. The knowledge about STD, pregnancy and available protection were not related with the use of protective methods. Approximately 20% of the sexually active adolescents did not use any contraceptives. In the year 2007, 250 gynaecological examinations were done, including cytological analysis, Chlamidia testing and pelvic ultrasound ( 25 CIN 1, 6 CIN 2, 12 ASCUS-a, 22 girls and 5 boys had a Chlamidia trachomatis infection, 7 girls were HPV positive). Conclusions: The needs of youth in the existing health system are not completely satisfied, and it necessary to form accessible multidisciplinary “Youth frendly services – open door counselling”. Health education of adolescents improves their knowledge of sexual behaviour, and also provides support and develops skills needed for avoiding risk-taking behaviour, as well as preventing STDs and unwanted pregnancies. The inclusion of adolescents in preventive programmes helps developing their capabilities, self-respect and responsibility in sexual behaviour.