Background: PEAK nasal inspiratory flow (PNIF) has been proposed as a simple method to evaluate nasal patency. Asthma and allergic rhinitis are commonly associated, and lower airway assessment can provide information concerning an objective interpretation of nasal function. Aims: TO determine whether the PNIF is correlated with peak expiratory flow (PEF) in children and adolescents. Methods and results: Cross-sectional study carried out in healthy students randomly chosen in 14 public schools of the city of Belo Horizonte. PNIF and PEF were assessed for each subject as the following characteristics: gender, height, weight and age. We created a linear regression model to explain the PNIF, in which we included all the variables with a p value ≤ 0.25 in a univariate analysis, and to calculate the relationship between the maximum PNIF and maximum PEF by the Spearman correlation coefficient. In total, 297 healthy subjects, aged between six and eighteen years were evaluated. A positive and significant correlation between PNIF and PEF was found. Conclusions: PEF is predictive of PNIF. However, these measures evaluate two distinct segments of the airways and should be both obtained for a more precise assessment of airflow limitation.