Cystic fibrosis (CF) is inherited as an autosomal recessive trait due to a mutated gene carried on the long arm of chromosome 7. The protein coded by the CF gene (CFTR) is an apical chloride channel that regulates active chloride transport across epithelial cell membranes. The role of CFTR in pancreatic exocrine secretion is based on the concept that CFTR is localized to the apical membrane of the proximal duct epithelial cells. The primary ductal cell chloride channel abnormality results in dehydrated protein-rich secretions that obstruct the proximal ducts, leading to secondary acinar cell destruction, fibrosis, and exocrine pancreatic insufficiency in 85% of the CF population. A strong correlation between genotype and pancreatic phenotype is recognized. Advances in molecular biology such as cloning of lipase genes and gene therapy are challenging the field of pancreatic enzyme supplementation therapy.