Mushrooms (Basidiomyceteae) are potent source of biologically active substances which have beneficial effect on human health. Many, if not all, mushroom species contain polysaccharides which may boost human immune system. The purpose of this research was assessing the content of crude water soluble polysaccharides (WSP) in three species of cultivated edible and medicinal mushrooms: Lentinula edodes, Pleurotus ostreatus and Agaricus blazei Murill. The content was determined both in caps and stems and the isolated WSP fractions were analyzed using FTIR spectroscopy. The results demonstrate that analyzed mushrooms species differ greatly in the WSP content. The largest amount was found in the fruiting bodies of Pleurotus ostreatus. On the contrary, the fruiting bodies of L. edodes contained the lowest amount of WSP. Furthermore, WSP in caps and steps are synthesized at a slightly different level. FTIR analyses suggest that there are no significant differences between chemical composition of crude WSP isolated from the stems and caps of the same species. The FTIR spectra of crude WSP also reveal polysaccharides and proteins patterns.