Interstitial lung diseases (ILD) are characterized by a variable degree of inflammatory and fibrotic changes within the alveolar space and distal airways (bronchioles). An inverse correlation exists between the extent of fibrosis and the possibility that an ILD is reversible. While the acute (inflammatory) type of extrinsic allergic alveolitis may resolve without sequelae (restitutio ad integrum), IPF is the prototypic fibrotic ILD with a progressive course, leading to an irreversible and progressive fibrosis of the lung parenchyma. This guideline provides guidance on differnential pharmacological treatment approaches to different types of fibrotic interstitial lung diseases.