Background: Balance is a fundamental movement skill crucial for activities of daily living and physical activity (PA), with poor balance being a risk for injury in both children and adolescents. Large numbers of young people are overweight and inactive. Low balance scores in young males are negatively associated with an increased weight status (BMI) and body fat percentage (BF%,). The negative effect of balance and motor performance is accepted, but the degree to which PA levels influence dynamic balance in adolescents has yet to be explored. Purpose: This study sought to examine the levels of dynamic balance in young people to investigate any correlation between the latter and BMI or Moderate to Vigorous Physical Activity (MVPA). Methods: One hundred and fifteen secondary school adolescents (55 girls, 60 boys mean age 13.92 years+/-.66) were assessed for height (m) and body mass (kg) using a Seca stadiometre and weighing scales (Seca Instruments, Germany) from which body mass index (BMI, kg/m2) was determined. The Y balance was used to assess dynamic balance. This is a reliable and valid tool for adolescents. The International Physical Activity Questionnaire was used to determine levels of habitual MVPA from which a dichotomous (high vs low MVPA calculated in METs) variable was created using a median split. Correlations between dynamic balance, MVPA and BMI were calculated. ANCOVA analysis enabled the differences in the dependant variables between fitness and gender groups to be analysed controlling for any impact of weight status whilst at the same time enabling the association between the dependant variables and the covariate to be determined. Results: Pearson's product moment correlations indicated a significant correlation (p = .0001) between dynamic balance and total METs (r = .403). A 2 (gender) by 2 (high vs low MVPA) way analysis of covariance (ANCOVA), controlling for BMI, indicated significant gender (p = .026) and MVPA level (p = .002) main effects. Girls, and adolescents with high MVPA, had better Y-balance scores than boys and adolescents with low MVPA respectively. BMI was not significant as a covariate (p = .177). Conclusion(s): The results of the present study suggests it is the level of physical activity (MVPA) not BMI that has a stronger influence on dynamic balance. Future research examining how MVPA interventions modify dynamic balance would be useful in understanding any cause and effect relationship between the variables studied here. Implications: This study suggests that dynamic balance appears to be associated with MVPA independent of BMI. Physiotherapy is promoting exercise as being important for general health, however the intensity should be considered in relationship to balance.