Cystic fibrosis (CF) is an hereditary disease with pancreatic insufficiency and chronic respiratory tract infections leading to irreversible lung damage as its main features. The typical pathogen for the respiratory disease is Pseudomonas aeruginosa. Although the insight into the pathophysiology and genetics of CF have evolved over the past 10 years, there is not yet a full understanding of the increased susceptibility for respiratory infections, specifically with Pseudomonas aeruginosa. In this overview we elucidate the current knowledge and describe the existing hypothesis on the possible links between the pathophysiological defects and the failure of the local defense mechanism in CF airways.