Abstract: One aspect of the invention provides a method of treating a subject diagnosed with cystic fibrosis, but not having a pathological bacterial colonization in either lung. The method includes administering gaseous nitric oxide at a concentration of between about 40 ppm and about 400 ppm to the subject's lungs wherein said nitric oxide is administered by inhalation, and further wherein said nitric oxide induces conformational change in the cystic fibrosis transmembrane conductance regulator (CFTR) in the cells of the lung of the subject. Another aspect of the invention provides a kit comprising: an apparatus for administering gaseous nitric oxide to a subject and instructions for administering the gaseous nitric oxide according to one or more of the methods described herein.