To find antitumor components in Korean basidiomycetes, the carpophores of Armillariella mellea which were collected in Gyeong Gi Province were extracted with distilled water at $90{sim}100^{circ}C$ for eight hours. The hot water extract was concentrated under reduced pressure, mixed with three-fold volumes of ethanol and allowed to stand at $4^{circ}C$ overnight. The precipitate was centrifugated and lyophilized to yield a protein-polysaccharide fraction. It was examined for antitumor activity against sarcoma 180 implanted in ICR mice. The fraction showed 75.7%, 83.9%, and 94.1% of tumor inhibition ratios at the doses of 10, 20 and 50 mg/kg/day, respectively. The chemical analysis of the fraction showed that it contained a polysaccharide(41.3%) and a protein (35.0%). The hydrolyzates of the polysaccharide moiety contained fucose (4.5%), xylose (1.1%), galactose (17.4%), glucose (55.4%), mannose(19.4%), and one unknown monosaccharide. The protein moiety contained seventeen amino acids. The protein-polysaccharide from A. mellea was administered, i.p., to mice and caused an influx of polymorphonuclear leukocytes (PMN) at $5{sim}24$ hours which was followed by an accumulation of macrophages and disappearance of the PMN at $48{sim}72$ hours.