Idiopathic pulmonary fibrosis (IPF) is a devastating disease with an almost universally terminal outcome. In recent years much insight has been gained into the pathogenesis of IPF from both a bleomycin mice-model as well as ex vivo human tissue studies. Alveolar damage and inflammation of unknown etiology, eventually leading to interstitial fibrosis, characterize IPF. Apoptosis has emerged as an important factor in the pathogenesis of IPF. This review will outline the current understanding of the immunological and molecular mechanisms underlying IPF, and discuss new therapeutic strategies.