BACKGROUND: In 2021, the Global Lung Function Initiative (GLI) has published new reference equations for static lung volumes (GLI-2021). Many learned societies recommend the use of GLI reference values for interpreting pulmonary function tests (PFT), while pointing out the need for clinicians to be aware of the consequences for their routine practice. We aimed to compare the GLI-2021 reference values and the 1993 European Coal and Steel Community (ECSC) standards on the interpretation of static lung volume data in patients with a probable static hyperinflation or a probable restrictive ventilatory disorder. METHODS: We analyzed plethysmographic PFT data from 2 groups of patients: a group of patients with symptoms compatible with chronic bronchitis (CB) and a group of patients with symptoms compatible with interstitial lung disease (ILD). We investigated discrepancies in the evaluations of static lung volumes when using the ECSC vs. the GLI-2021 reference values. RESULTS: 2,897 sets of PFT results (including 1,598 in men) were included. In the CB group, the proportion of hyperinflation was higher for both sexes with the GLI-2021 standards. In the ILD group, the proportion of restrictive ventilatory disorders was higher in women but lower in men with the GLI-2021 standards. CONCLUSION: A move from use of the ECSC standards for static lung volumes to the GLI-2021 standards might lead to a higher estimated proportion of hyperinflation (particularly in participants with CB), together with changes in the proportion of restrictive ventilatory disorders (a lower value in men and a higher value in women with ILD).