Polysaccharides from plants have been the subject of study for a very long time, but mainly for their physical properties and industrial use based on these properties. Over the last 20 years there has been an ever increasing interest in the biological activity of biomolecules. These studies became possible as a result of the scientific development of isolation, purification and characterisation methods concomi-tant with the development of fairly simple in vitro tests, especially for effects on the immune system. The growing acceptance of the knowledge to be gained by people still using so-called traditional medicine in finding sources worthy of investigation has led to new sources for interesting bioactive plant polysaccharides. This review covers only a small part of the field it focuses primarily on the pectic type polymers and their activity some important neutral polysaccharides like lentinan and acemannan are mentioned as well as methods used for these studies.