Conventional techniques of chemical analysis have shown that the cell walls of the yeast Pichia polymorpha, at early stationary growth phase, consisted of carbohydrate (about 85%), protein (8%), and lipid (7%). Glucose and mannose were the only neutral sugars and glucosamine the sole amino sugar present among the cell wall components. Paper and gas-liquid chromatographies of acid hydrolysates of purified cell walls and cell wall fractions proved that mannan and alkali-insoluble glucans, in that order, were the major polysaccharide components, accounting for 83% of the total carbohydrate content. The isolation of an alkali-soluble glucan, non-precipitable with Fehling's solution, has been achieved. Treatments of whole cell walls and their fractions with purified cell wall lytic enzymes have shown the presence of both 1,3- and 1,6-beta-D-linkages in all the glucan fractions. 1,3-alpha-Glucan was not detected. Mannan-glucan complexes have been found containing about 50% each of mannose and glucose. All polysaccharides exhibited different turnover rates when cells were grown in the presence of D-[U-14C]glucose. The morphogenetic implications of these results are discussed.