While the care of cystic fibrosis (CF) patients has been mainly the province of pediatricians, great improvements in the therapy and life span of CF patients often results in their transition to care by adult physicians. In this review of CF, we begin with an overview of the epidemiology and genetics of the disease, with a discussion of the recently found ion abnormalities that lead to the clinical manifestations. This is followed by a discussion of the pathophysiology. Methods of diagnosis, ranging from the gold standard, the sweat test, to recent advances based on a greater understanding of the genetics of the disease are reviewed. This is followed by a discussion of therapy primarily geared to the treatment of the respiratory complications, as they are the most common lethal factors of the disease. We point out controversies where they exist. Newer forms of therapy such as lung transplantation are discussed, and we finish with a discussion about future therapeutic modalities, some of which are being approved as the paper is in print.