Although the application of thoracic high-resolution computed tomography (HRCT) to clinical pulmonology has revolutionised the diagnostic approach to patients with suspected interstitial lung disease (ILD), additional testing is often needed to make a confident ILD diagnosis. Bronchoalveolar lavage (BAL) can play a significant role in making an accurate and confident diagnosis of specific forms of ILD. When BAL is used in conjunction with comprehensive clinical information and HRCT, BAL nucleated immune cell patterns can frequently provide useful information for diagnostic evaluation and lessen the need to proceed to more invasive procedures, such as surgical lung biopsy. Additionally, BAL can identify confounding conditions, such as infection or malignancy. However, BAL technique, and protocols for processing and analysing BAL fluid are critically important for providing useful information. This perspective reviews the current status of using BAL as a diagnostic tool for the diagnosis of ILD.