To investigate constituents of Russula pseudodelica Lange and Microporus affinis(Blume et Nees) Kuntze, quantitative analyses of free and total amino acids were carried out with G. L.C. and an amino acid autoanalyzer. Polysaccharides of the two mushrooms were extracted with hot water and the filtrate was concentrated. The addition of three volumes of ethanol to the concentrate formed precipitation of crude polysaccharides which were analyzed by G.L.C. and H.P.L.C. Sixteen amino acids and four monosaccharides were identified in the protein-bound poly­saccharides of the two mushrooms. The polysaccharides of M. affinis showed antineoplastic activity against sarcoma 180 implanted in mice.