Four polysaccharides from the water extract of cultured Cordyceps militaris were isolated through ethanol precipitation, deproteination and gel-filtration chromatography. Their molecular weights were determined using gel-filtration chromatography. Among the four isolated polysaccharides, the structures of two of them (CPS-2 and CPS-3) were elucidated by sugar analysis, Smith degradation, IR and (13)C-NMR spectroscopy.