• The distribution of major erythrocyte phospholipids and fatty aldehydes and the total fatty acid composition of erythrocytes and plasma were compared from patients with Duchenne's muscular dystrophy, from definite carriers of the disease, from patients with myotonic atrophy, and from a number of normal controls. The data for normal controls closely agreed with the accepted values for these lipid components. Contrary to the published reports of others, no abnormalities in lipids were found in either disease or carrier groups.