Objective To investigate the development of sexuality from early to late adolescence,and to compare girls and boys of different agesMethods A cross sectional survey in all schools was performed covering all pupilsbetween 13 and 18 years of age that were in school when the survey was conducted. Avalidated instrument, Q90, created for use in teenagers was distributed in the class-rooms to 3 216 teenagers. Q90 covers 30 questions about body development andsexual behavior. Non-response was insignificant (n=19; 0.6%).Results Pubertal development was considered “early” or “late” by about 50% ofboth boys and girls. Eighty percent of the 13 to 15 years old boys and girls had had aromance and 30% had experience of sexual cuddling (petting), while significantlymore girls than boys had sexual intercourse (18% vs 13%; odds ratio 1.5, 95% CI1.1-1.9). The difference between girls and boys remained in those being 16-18 yearsold, where 63% of the girls and 53% of the boys (odds ratio 1.5, 95% CI 1.2-1.9)admitted having intercourse. Mean age at first intercourse was 14.9 and 15 years,respectively. At 16-18 years of age, 23% of the sexually active girls, as compared with25% of the boys estimated that they had had 6 or more sexual partners. About 30% ofthe adolescents, irrespective of age and gender, did not use contraceptives at theirfirst and latest intercourse. Eight percent of the older girls had been pregnant, andthey had an increased history of sexually transmitted infections, as compared withthe boys (6.2% vs 2.7%; odds ratio 2.4, 95% CI 1.2-5.0).Conclusion Exploring sexuality and experimentation is a normal behavior inadolescence. The results of this study, however, indicate that there are substantialgroups of teenagers who practice sexual risk-taking. In addition to general sexualeducation, programs should also be directed to define sexual risks and its consequences. Objective To investigate the development of sexuality from early to late adolescence, and to compare girls and boys of different ages. Methods A cross sectional survey in all schools was performed covering all pupilsbetween 13 and 18 years of age that were in school when the survey conducted conducted. Avalidated instrument, Q90, created for use in teenagers was distributed in the class-rooms to 3 216 teenagers. Q90 covers 30 questions about body development andsexual behavior. Non-response was insignificant (n = 19; 0.6%). Results Pubertal development was Eighty percent of the 13 to 15 years old boys and girls had had aromance and 30% had experience of sexual cuddling (petting), while significantlymore girls than boys had The difference between girls and boys remained in those being 16-18 yearsold, where 63% of the girls and 53% of the boys (18% vs 13%; odds ratio 1.5, 95% CI 1.1-1.9) odds ratio 1.5, 95% CI 1.2-1.9) have having intercourse. Mean age at first intercourse was 14.9 and 15 years, respectively. At 16-18 years of age, 23% of the sexually active girls, as compared with 25% of the boys estimated that they had had 6 or more sexual partners. About 30% of the adolescents, irrespective of age and gender, did not use contraceptives at theirfirst and latest intercourse. Eight percent of the older girls had been pregnant, andthey had an increased history of sexually transmitted infections, as compared with the boys (6.2% vs 2.7%; odds ratio 2.4, 95% CI 1.2-5.0) .Conclusion Exploring sexuality and experimentation is a normal behavior in adolescence. The results of this study, however, indicate that there are substantial groups of teenagers who practice sexual risk-taking. addition to general sexualeducation, programs should also be directed to define sexual risks and its consequences.