There is a significant amount of experimental evidence suggesting that polysaccharides from mushrooms enhance the host immune system by activating various mechanisms in immune cells, including macrophages. In this study, polysaccharides from Lentinus edodes were found to stimulate the functional activation of macrophages to secrete inflammatory mediators and cytokines and increase the phagocytotic uptake. The chemical properties of the stimulatory polysaccharides, CPFN-G-I, CPBN-G, and CPBA-G, were determined based on their monosaccharide composition, which mainly consisted of glucose and mannose. According to FT-IR and GC/MS, the structure of CPFN-G-I, purified from the fruiting body of L. edodes, was found to consist of a beta-1,6-branched-beta-1,4-glucan, whereas CPBN-G and CPBA-G, purified from the liquid.