It is now well established that surfactant dysfunction plays an important role in the development and progression of ILD. Pulmonary surfactant is a multimolecular complex constituted of phospholipids and proteins secreted by type 2 AEC into the alveolar space. It assures alveolar stability by reducing surface tension along the epithelial lining and this role involves mainly the lipids and the specific hydrophobic SP, SP-B and SP-C. Other important players in surfactant metabolism include the ATP-binding cassette, sub-family A, member 3 (ABCA3) and the thyroid transcription factor 1 (TTF-1).