Aim. The aim is to study the health-related quality of life in a school sample of children and adolescents aged 8-18 years and to examine the relationship between health-related quality of life and the following variables; age, gender, perceived pain, body image, body mass index and bullying. Background. The study of health-related quality of life in children and adolescents have received little attention compared with adults in health care research and still little is known about the associations between health-related quality of life and other variables. Design. A cross-sectional design was chosen. Method. We measured the health-related quality of life using the generic questionnaire KIDSCREEN-10. We administered the KIDSCREEN 52-item, and the 10 items were selected from this according to the KIDSCREEN manual. Multilevel regression models were used to evaluate the associations between health-related quality of life and the independent variables. Results. The sample included 1066 children and adolescents, 576 girls and 490 boys, with a response rate of 74%. The results show that body mass index was not significant associated with health-related quality of life in full model. However, in addition to age, being bullied, pain and body image were significant associated with health-related quality of life. Of these predictors, body image has the strongest impact in terms of explained variance in health-related quality of life. Conclusion. The subjective sense of satisfaction or dissatisfaction with one's body, perceived body image, is a powerful predictor of health-related quality of life. Relevance to clinical practice. Knowledge about predictors of health-related quality of life is especially important for public health nurses. Health promotion and intervention programmes that aim to strengthen psychosocial well-being, especially those that strengthen body image, should be developed for both genders.