The cell wall fraction was isolated from cytoplasm by sonicating and washing the mycelia of Cochliobolus miyabeanus, and its chemical composition was studied. The cell wall was constituted by the polymer of neutral sugars (51.68%), amino sugars (38.03%), peptide (10.75%), lipid (0.57%) and ash (2.33%). A great deal of α- and β-glucose and traces of galactose, mannose, arabinose, rhamnose, fucose and xylose were found in the hydrolysate of poly neutral sugar fraction, and amount of glucosamine and trace of galactosamine in the hydrolysate poly amino sugar fraction by gas liquid chromatography (GLC) and paper parttion chromatography (PPC) analyses. When these two fractions were allowed to react with α- or β-glucosidase and chitinase, glucose was liberated from neutral sugars fraction only when β-glucosidase was used, and acetyl-glucosamine was liberated from amino sugars fraction by chitinase. Sixteen kinds of amino acids were detected from peptide on amino acid analyser. From these results, it is concluded that the cell walls of our fungus are constituted with β-glucan and chitin-like layers associated with a small amount of other sugars and peptides.