Bronchoalveolar Lavage (BAL), is a minimally invasive method performed via bronchoscopy, and has been essential to obtain samples which may provide information about the inflammatory status, and infectious conditions of the alveoles. BAL is very substantial procedure for diagnosing especially interstitial lung diseases but also important other pulmonary diseases such as pulmonary alveolar proteinosis, alveolar hemorrhage, malignancy, Langerhans cell histiocytosis. The most important issue regarding a BAL procedure is the qualification and adequacy of the sample. Cell counting and culture, pathologic evaluation should be performed in every sample by certain staining methods.