Cystic fibrosis, a disease thought to be transmitted as a recessive genetic trait, is found as a disease in about one in 1,000 to one in 10,000 births. It involves all of the exocrine glands with presenting symptoms dependent upon the extent of involvement of any group of glands. Many aspects of the disease can be corrected by substitution therapy. This applies particularly to the use of animal pancreas for the steatorrhea and salt for prevention of heat prostration. Unfortunately, the obstructive pulmonary disease with secondary bronchial infections can only be treated symptomatically by the use of mucus thinning agents, postural drainage, and antibiotics. Nevertheless, longevity can be increased and a great deal of hope offered to the families of these unfortunate children by careful supervision of their medical care.