A polysaccharide mixture, fraction A, was extracted from the mycelia of Poria cocos (SCHW.) WOLF with 1 N KOH solution and precipitated with ethanol. Fraction A showed a strong antitumor effect against implanted sarcoma 180 (solid type) in mice. Fraction A was fractionated into two fractions F₁ ([α]_D²⁶+120°) and F₂ ([α]_D²⁶+170°) by salting out with ammonium sulfate and subsequently by DEAE-Sephadex A-25 column chromatography. Furthermore, the antitumor active fraction F₁ was separated into three fractions H₁₁, H₁₂ and H₂ by affinity chromatography by use of Con A-Sepharose. Of these three fractions, only fraction H₁₁, homogeneous on electrophoresis, showed a strong antitumor effect. On complete hydrolysis, fraction H11 gave D-glucose as a sole product. It is suggested that the glucosidic linkage in fraction H11 has a β-configuration from the negative low specific rotation ([α]_D²⁶-28.2°) and absorption at 890cm^-1 in the infrared spectrum.

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