AIM: To compare different areas of adolescent behaviors and self-perceived health with the aim of identify'ing age and gender differences to facilitate planning of public health preventive measures. METHODS: A cross-sectional survey in ten Swedish schools covering all students between 13 and 18 years of age. A validated instrument, Q90, created for use in teenagers, was distributed in the classrooms to 3,216 teenagers. RESULTS: In all age groups, girls had significantly more problems regarding self-perceived health, i.e., general health, abdominal pain, headache, feeling depressed, and suicidal thoughts, than boys. Ingirls, proportion feelingdepressed increased from 28% inthe youngest group (11% in boys) to 51% in the oldest (20% in boys). Similar results were found for all health-related problems. Significant differences were found between both gender and age groups in experiences of being bullied. A significantly higher frequency of boys than girls admitted to committing vandalism (35% vs. 11% in the oldest age group). The frequency of girls feeling overweight increased moderately with age, from 35% at age 13 y to 50% at age 18 y. The proportion of boys feeling underweight increased more distinctly, from 8% at age 13 y to 29% at age 18 y. Tobacco use and alcohol habits were similar in gender comparisons. CONCLUSION: The study demonstrates areas of normative development from early to late adolescence. The striking differences in health perception between girls and boys must be stressed. The results might form a basis for teachers, school health workers, and other health authorities working with adolescents.