This protocol is designed to evaluate the ability of a Replication Deficient, recombinant adenovirus vector to transfer the normal human cystic fibrosis transmembrane conductance regulator c DNA to the respiratory epithelium of individuals with cystic fibrosis. Study individuals will undergo a series of studies at designated intervals to evaluate safety and efficacy of this therapy. These tests include: general assessment, blood and urine studies, EKG, chest x-ray, lung function tests, sputum culture, and bronchoscopy. At completion of the study the following questions will be answered: (1) Is it safe to administer such a vector in this fashion to individuals with CF?; (2) Will the vector transfer the normal cDNA such that it is expressed in the airway epithelium and will correct the biologic abnormalities; (3) Is there improvement in clinical signs and symptoms relevant to CF?; and (4) Does this therapy evoke humoral immunity?