Introduction: In the adolescence period, an individual experiences biopsychosocial changes and dissatisfaction with body image is quite prevalent at this stage. Objective: To investigate the prevalence of body image dissatisfaction and its association with demographic and psychosocial factors, sexual maturity, nutritional condition and lifestyle. Method: Cross-sectional study with a sample representing 831 eighth grade students from Porto Velho, Rondônia, Brazil, stratified into clusters. The data were obtained by questi onnaires - the Body Shape Questionnaire and Global School-based Student Health Survey - and anthropometry. The associations of interest were tested in a multivariate analysis with Cox regression adjusted for cross-sectional studies. Results: The prevalence of body image dissatisfaction was 22 per cent. The outcome was signifi cantly more prevalent among girls (PR: 4.69; CI: 95%: 3.09 – 7.12), young Caucasians (PR: 1.32; CI: 95%: 1.02 – 1.72), those who used tobacco (RP: 1.53; CI: 95%: 1.12 – 2.09), who were overweight or obese (PR: 2.77; CI: 95%: 2.18 – 3.51), and who reported feelings of sadness (PR: 1.35; CI: 95%: 1.05 – 1.73) and loneliness (PR: 1.66; CI: 95%: 1.30 – 2.11). The students with lower weight were more satisfied with their image. Conclusion: The results point to the need for parents, educators and health professionals to act jointly in developing actions that reinforce the positive qualities of youth, especially in girls. Encouraging physical activity and healthy habits can promote overall health, improving satisfaction with body image.