The scope of this study was to evaluate body dissatisfaction among adolescents, and to explore differences according to sex, socioeconomic status and body mass index. 4325 individuals aged 14-15 years old from Pelotas, Brazil, were studied. Body dissatisfaction was evaluated comparing the desired image with the perceived image, according to the Tiggemann & Wilson-Barret silhouette scale. The nutritional status was categorized in accordance with World Health Organization criteria, whereas socioeconomic status was evaluated using classifications of the Brazilian Association of Research Institutes. It was found that 27.6% of teens were overweight. Body dissatisfaction, appraised by the silhouette scale, affected 51% of boys and 65.6% of girls. The economic and nutritional status was associated with the outcome. Most overweight adolescents wished to have a slimmer silhouette than the perceived one. The economic level modified the effect of nutritional status on body dissatisfaction. Adolescents from the wealthier economic classes who were not in the ideal weight range manifested greater body dissatisfaction than the less affluent individuals and, irrespective of economic status, girls are more dissatisfied with excess body weight and boys with slimness.