Animal models can provide considerable benefit for investigating the pathogenesis of the complex process of fibrosis in the lung. Systems include intratracheal administration of various chemical profibrotic agents such as bleomycin, gene overexpression or irradiation to mimic human pulmonary fibrosis; however, concerns regarding the direct transferability of findings to clinical disease exist. This review highlights advantages and deficiencies of different animal models of fibrosis and discusses their role in finding new treatment options for IPF-patients. © 2006 Elsevier Ltd. All rights reserved.