To find antineoplastic components from Korean higher fungi, the mycelium of Ganoderma lucidum (Fr.) Karsten was grown in shake culture and a protein-bound polysaccharide was isolated. This component suppressed tumor growth of sarcoma 180 grafted in A-strain mice. The component was administered intraperitoneally to the mice at a dose of 50 ㎎/㎏ daily for five days. Ten days later, the mice were immunized with 1×10^7 sheep red blood cells. The number of plaque-forming cells in their spleen was significantly greater than that of control mice. Three monosaccharides and sixteen amino acids were identified from the protein-bound polysaccharide.