Improvements in biological research and the development of new techniques for human health protection require animal experimentation of various species. In particular, animal models are always necessary to test new therapies for the treatment of various human diseases. The latest advances in molecular biology involving genetic modification are aimed at developing new animal models of human diseases that are not present in spontaneous murine broods or obtainable with other experimental manipulations. Transgenic techniques and, in particular, the possibility to directly modify specific genetic information in the experimental animal have led to the acquisition of important knowledge on the physiologic functions of many proteins and their function in the course of various diseases. The advent of new transgenic animals is opening up new and interesting frontiers, full of hope and opportunity, for the research into pulmonary diseases. New advances in cystic fibrosis, emphysema, and pulmonary fibrosis have been made through the study of a large number of proteins implicated in the complex of acute and chronic inflammatory processes of lung parenchyma, which are responsible for permanent changes in organ structure and function. Recent studies carried out on murine inbred strains have yielded significant new data on the multifactor origin of pulmonary disease, because of their correlation with the major histocompatibility complex (H2 in mice) or through the different genetic map of the strains. Today it is possible to outweigh or potentiate the function and expression of some genes, obtaining a deficit or abundance, respectively, of specific proteins. These techniques have permitted and will continue to permit the development of new models of human disease, leading to further therapeutic advances as a consequence.