Cystic fibrosis (CF) is the most common autosomal recessive disease with fatal outcome in Caucasians with a frequency of 1 in 2500 life births. It is caused by mutations in a single gene on the long arm of chromosome 7 encoding a protein called the cystic fibrosis transmembrane regulator (CFTR). The defect in CFTR leads to pathological changes in all organs with mucus-secretory glands, e.g. airways, pancreas, gut, biliary tract, vas deferens and sweat glands. Despite impressive advances in understanding the molecular basis of the disease, life expectancy is still limited in CF and chronic infection of the lung resulting in fibrosis and bronchiectasis followed by respiratory insufficiency is still the main factor in morbidity and the leading cause of death. Poor nutritional status is one of the major problems in the vicious cycle of chronic inflammation and lung destruction and its impact on outcome in lung function has been demonstrated. The possible role of growth hormone treatment in this context will be discussed.