The cell walls of Clostridium sordellii and Cl. bifermentans agreed in their amino acid and amino sugar pattern, but differed strikingly in their monosaccharide patterns. Sixteen Cl. sordellii strains contained only glucose as monosaccharide in their cell walls, whilst in Cl. bifermentans three sugars were found: in 13 strains glucose, mannose and rhamnose and in the 3 others glucose, galactose and rhamnose. The sugar pattern in formamide extracts of cells is sufficient for diagnostic purposes.