Cystic fibrosis (CF) is an autosomal recessive inherited metabolic disease. The mutation is located on the long arm of chromosome 7. Due to a defect in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, chloride ion transport is reduced across the cell membrane. As a result, the disease can be described as an exocrinopathy. In all organs with exocrine glands, disorders occur in association with the defective chloride transport. The main impact of this defect is manifested in the lungs. Therefore, the most common cause of death is pulmonary disease with respiratory insufficiency due to recurrent infections. Unfortunately, a cure for the disease is still not available. However, new therapies that may affect the CFTR mutation more specifically give new hope for better therapeutic options in the future. The long-term goal of therapy is to develop a causal therapy for all six different mutation classes and thus for about 2000 mutations.