Nowadays, preoccupation with body image has taken on an increasing role, with human behaviour being influenced by the media and by society-imposed “beauty standards”. Not achieving the ideal of beauty can cause body dissatisfaction and may lead to low self-esteem. The aim of this study was to evaluate body perception, dissatisfaction with body image and the influence of the media in adolescents. N=450 adolescents aged 14 to 16 years, of both sexes, from public and private high schools participated. Three survey tools were applied: the Figure Rating Scale, the Body Shape Questionnaire and the Sociocultural Attitudes towards Appearance Questionnaire. 47.1% of the public school girls presented some level of dissatisfaction. The girls had a poorer perception of their BI than the boys, judging that they had a thinner figure than in reality. Adolescents internalize messages from the media regarding established beauty standards and experience pressure to achieve a “perfect body”, with private school girls being the most influenced. The increased influence of the media on adolescents is related to the increase in body dissatisfaction. Adolescents of both sexes, from different cultures and socioeconomic levels are influenced by beauty standards established by the media which can be determinant to increasing dissatisfaction with the size and/or shape of the body, leading them to unhealthy behaviours aiming to achieve "ideal beauty". Such behaviours are associated with the etiology of eating disorders, which may become a major public health problem.