AIMTo determine the knowledge of adolescents living in Mostar, Bosnia and Herzegovina, about contraception and sexual health.METHODSWe used an anonymous questionnaire to survey a random sample of 120 high school students, 60 from two general high schools and 60 from a vocational school. There were 30 male and 30 female students aged 15-17 years from each type of school. The questionnaire consisted of 24 questions: 17 tested the students' knowledge on the menstrual cycle, contraception, emergency contraception, and sexually transmitted diseases (STDs), and six inquired how they obtained the information on these issues. Student t-test was used to test for score differences between male and female students, and between general high school and vocational school students in their general and specific knowledge. Pearson's r coefficient was used to test the correlation between average grades and knowledge.RESULTSFemale students had greater general knowledge (t=3.69, df=118, p<0.001), knowledge on contraception (t=3.66, df=118, p<0.001), and knowledge on STDs (t=2.71, df=118, p=0.008) than their male peers. General high school students also had greater general knowledge (t=2.44, df=118, p=0.016), and knowledge on contraception (t=2.18, df=118, p=0.031) or STDs (t=2.36, df=118, p=0.020) than their vocational school peers. Major sources of information were magazines (69%), TV/radio (50%), school (37%), and friends (36%). The most common reason that kept our examinees from obtaining information on these issues was shame (52%). The two most common contraception methods known to them were a condom (82%) and contraception pill (77%), whereas 17% of all students were unfamiliar with any contraception method. When asked what could be done to improve their knowledge on sexuality, contraception, and STDs, most students opted for the inclusion of sexual education into the school curricula.CONCLUSIONFemale students knew more about contraception and sexual health than their male peers. Young people should be provided with more information on sexual health.