ObjectiveBronchoalveolar lavage (BAL) is a diagnostic tool often used during the management of interstitial lung diseases (ILD). However, its diagnostic value in discrimination between entities comprising the very heterogenous group of ILD, is still a controversial issue. The objective of our study is to assess the diagnostic value of BAL in the management of ILD, by comparing the cytological findings in BAL fluid among the different diseases of this group.MethodsIt was a retrospective, observational study of 151 patients between January 2012 and December 2015. BAL fluid cytology was performed to analyse the distribution of leucocytes population subsets in patients with ILD.ResultsThe mean age was 52.78 years; 74.83% were women. The analysis of the following main groups of diseases was performed : sarcoïdosis (n = 30), idiopathic pulmonary fibrosis (IPF; n = 22), other idiopathic interstitial pneumonia (non specific interstitial pneumonia, cryptogenic organising pneumonia and respiratory bronchiolitis interstitial lung disease; n = 20) and connective tissue disease (n = 14).Overall, out of 141 patients, 22% had sarcoïdosis, 15.6% had idiopathic pulmonary fibrosis (IPF), 14.18% had other idiopathic interstitial pneumonia (IIP) and 9.9% had connective tissue disease (CTD). Mixed alveolitis was common in the 4 groups, sarcoïdosis had higher proportion of lymphocytes and IPF had higher neutrophils count. However, there was no significant statistical difference of BAL cellular count among these diseases (p > 0.05). Also, the prevalence of studied diseases did not change with variation of BAL cellular count (p > 0.05).ConclusionAlone, the BAL cytological analysis has a limited value to provide substantial information that could lead to discriminate between diseases that form ILD. Thus, it must be always associated with other diagnostic methods.