Two disaccharides have previously been obtained in high yield from the cell wall of Staphylococcus aureus by the use of hydrolytic enzymes. Disaccharide 1 is N-acetylglucosaminyl-N-acetylmuramic acid and disaccharide 2 is N-acetylglucosaminyl-N,O-diacetylmuramic acid. After hydrolysis of disaccharide 2 with 0-acetylglucosaminidase, N,O-diacetylmuramic acid was prepared. Data obtained from periodate oxidation of these compounds coupled with their susceptibility to 0-acetylglucosaminidase indicate that both disaccharides are p-1,4- linked and that the 0 acetyl group of disaccharide 2 is on the 6- position of N-acetylmuramic acid. The high reducing power and positive Morgan-Elson reaction of the disaccharides are due to their unusual susceptibility to hydrolysis at alkaline pH. These and other anomalous properties of the compounds are discussed in relation to data previously obtained (J.-M. Ghuysen and J. L. Strominger (1963), Biochemistry 2, 11 19).