Background: Physical fitness along with the Body Mass Index (BMI), are necessary for making decisions regarding health, allowing the implementation of physical activity programs in the school. Aim: a) To relate BMI to self-perception of physical fitness and b) to verify the differences in the self-perception of physical fitness of adolescents with and without excess body weight. Methods: A descriptive (correlational-comparative) study was carried out. 306 adolescents (123 males and 183 females) were selected in a non-probabilistic (accidental) form with a age range between 14.0 and 18.9 years. Weight and height were evaluated. The Body Mass Index (BMI) was calculated. A scale was used to measure self-perception of Physical Fitness. Results: BMI was negatively related to the self-perception of physical fitness of adolescents of both sexes. In men, the ratio was R2 = -0.283 and in R2 = -0.145. In the comparisons related to the physical fitness dimensions between adolescents with and without excess weight, significant differences were observed in both sexes (p <0.05). Conclusion: It was determined that a high BMI adversely affects the self-perception of the physical fitness dimensions of adolescents of both sexes. These results suggest that the perception of the morphological, muscular, motor and cardiovascular dimension should be stimulated and worked in schools to promote physical activities, especially in adolescents with excess weight.