Cystic fibrosis (CF) is an inherited multisystem disorder characterized chiefly by obstruction and infection of airways; pulmonary complications are the most serious complications in CF. Since the localization of the CF gene in 1989 on the long arm of chromosome 7 was defined, knowledge about the pathogenesis of the disease has rapidly increased. On the other hand, the exact mechanism for how an abnormal gene leads to disease still remains unclear. In this article, the pathogenesis of CF lung disease is reviewed based on the recent literature, focusing on genetics, molecular defect, physiologic mechanisms that regulate mucus, infection and inflammation. Anahtar Kelimeler : kistik fibrozis, genetik, patogenez,cystic fibrosis, genetics, pathogenesis.