Altered fatty acid composition (decreased linoleic acid and increased palmitoleic and oleic acids) is found in blood and tissue lipids of patients with cystic fibrosis. Although these alterations are related to the malabsorption and maldigestion associated with pancreatic insufficiency in the CF patient, recent investigations suggest that the lower caloric intake of the CF patient relative to their caloric requirements compared to normal individuals may lead to increased utilization of absorbed essential fatty acids (i.e.: linoleic acid). Such increased metabolism of linoleic acid would explain the altered fatty acid composition observed. The decreased linoleic acid content as observed in most cystic fibrosis patients is associated with decreased unsaturation in tissue phospholipids and membranes. This characteristic may relate to changes in membrane function as well as altering prostaglandin synthesis. Current work is aimed at delineating the role of abnormal fatty acid composition of blood and membrane lipids as a cause of alterations in the recognition or interaction of the Beta-receptors in CF tissues and alteration in the availability of arachidonic acid for the biosynthesis of prostaglandins.