The bronchodilator responsiveness testing (BDR) is of great value for clinical decision-making. In children, the BDR interpretation differs depending on the guidelines. A new method was recently proposed based on ?FVC and/or ?FEV1>P10% (ATS/ERS 2021). Objectives: To compare the different methods for valuing BDR in children with normal spirometry and different degrees of bronchial obstruction and to study if BDR interpretation through fixed volume and FVC cut-offs in children is of value. Methodology: Data from 2272 tests performed at a Pediatric Lung Function Lab in 4 years (2017-2020) were reviewed. Descriptive and comparative analysis of different equations for FEV1 and FVC variations, as recommended by different societies was done: 1. ATS/ERS 2005: ?FVC and/or ?FEV1 ?I(initial)12% and ?200ml; 2. ATS/ERS 2021: ?FVC and/or ?FEV1 >P10%; 3. GINA 2022: ?FEV1 >P12%; 4. NAEPP 2007: ?FEV1 ?I12% and >200ml; 5. SATS 2013: ?FEV1 and/or ?FVC ?I12% or >200ml; 6. BTS 2019: ?FEV1 ?I12% (Student's T-tests; Q-Crochan and ANOVA; SPSS v.25). Results: From 2201 tests, 56% were from male children, mean age 12 (±3) years. Predominant referral diagnosis was Asthma (1718; 78%). In basal spirometries, the variation of the mean values for FEV1 and FVC significantly increased with age. For BDR, significant differences between the different equations were found. The FEV1?200ml criterion was the most often criteria for a positive test followed by ?>10%P. Conclusion: Due to differences in lung volumes with increasing age, the use of fixed volume cut-offs in children as positivity criteria for the BDR should be discontinued. The new ERS/ATS 2021 interpretative criteria based on ?>10%P seem to be more appropriate.