Current society has a high rate of sedentarism, including in children and teenagers. Low levels of physical activity, physical fitness and high body mass index are related to the development of chronic degenerative diseases, such as: diabetes, sedentary lifestyle, cardiovascular problems, cancers and others. Through this research, the objective of the study was to evaluate the influence of physical activity level and body mass index on physical fitness in high school. The sample consisted of 30 high school students of both sexes with ages ranging from 14 to 17 years old. The participants were submitted to the IPAQ questionnaire - short version, anthropometric measures (weight, height, wingspan and waist circumference) and physical tests of flexibility, abdominal strength and cardiorespiratory resistance, according to PROESP-BR 2016. The results obtained in relation to the characterization of the sample show significant differences between genders (p≤0.05), regarding body mass (male 64.32 ± 8.71 and female 56.72 ± 10.83), height (male 173.41 ± 9.16 and female 160.60 ± 4.37) and wingspan (male 174.45 ± 8.06 and female 161.08 ± 5.73). They also showed a significant difference between the genders (p≤0.05) in the abdominal test (male 38.54 ± 7.67 and female 23.59 ± 6.83) and running test (male 842.39 ± 89.06 and female 719.65 ± 78.24). The categorical associations between BMI and Waist/Stature Relationship; and BMI and abdominal strength test showed significant associations (p≤0.05). It was concluded that the Body Mass Index may be associated with the classification of the abdominal test result and waist-to-height ratio, with no significant association between the other tests. There is also no significant association between the level of physical activity and the physical tests.