Interstitial lung diseases (ILDs) are inflammatory diseases characterized by slow and progressive destruction of alveolar-capillary functional units, often leading to respiratory failure and death. A first stage of alveolitis and a following stage of fibrosis provoke an anatomical distortion of the peripheral airways and the interstitium, and for their smoldering evolution and non-specificity of symptoms ILDs may remain undiagnosed and untreated for a long time. In this review we exploited the immunopathogenetic aspects and the therapeutical approaches to this frequently unrecognized and severe disease.