Five Ganoderma species, including G. lucidum, G. tsugae, G. oerstedii, G. resinaceum and G. subamboinens, were parallel studied under an identical condition. These species were cultivated using liquid fermentation and their mycelia polysaccharides were extracted and compared on the physical/chemical properties and in vitro immunomodulatory activities. These results showed that the polysaccharide yields varied markedly among different species, and G. oerstedii was the highest among the five. However, HPLC analysis showed all the polysaccharide extracts had similar molecular weight distributions and monosaccharide compositions. They all contained glucose, galactose, mannose, glucosamine hydrochloride and fucose. In vitro assays, these polysaccharide extracts significantly stimulated phagocytosis and nitric oxide production by RAW 264.7 macrophage cell line, and G. subamboinens exerted the strongest potency. When Con A was not or presented, they all showed an up-or-down immunomodulatory effect on mouse splenocyte proliferation. The results illustrate that in addition to G. lucidum and G. tsugae, which are the two mostly studied and applied species, other Ganoderma species can also produce polysaccharides with similar physical/chemical properties and with similar immunomodulatory activities.