TO THE EDITOR : BAL is routinely performed in the diagnostic workup of interstitial lung diseases. Cell count of leukocyte subsets provides important clues to either confirm or rule out specific diagnoses. The latest guidelines on idiopathic pulmonary fibrosis (IPF) diagnosis include BAL as an important step in the diagnostic process, either to rule out a specific diagnosis or to confirm IPF in the absence of lymphocytosis or the presence of neutrophilia. Besides, some studies suggest that high BAL eosinophil (> 1%) and neutrophil (> 10%) counts constitute predictive biomarkers of IPF severity. However, this has been poorly prospectively evaluated, especially since the advent of antifibrotics.5 Furthermore, existing studies have included small populations and yielded conflicting results, notably on the link between BAL eosinophils and mortality. Therefore, we investigated the correlation between BAL cell count, longitudinal pulmonary function tests (PFT), and IPF-related death and exacerbations in a multicentric prospective cohort of patients with IPF. [.]