To investigate anti-complementary activity from the Korean wild edible plants. thirty kinds of plant hot water extracts were assaysed and IgM-sensitized sheep erythrocytes. Among them, several plants, that is, Pteridium aquilinum. Osmunda japonica, Amaranthus ascendens, Aralia elata, Ligularia fischerrii and Adenophora triphylla showed considerable activity more than 60% of ITCH_(50) value in comparison with control. Sodium periodate oxidation and pronase digestion of these active fractions revealed that the complement activating ability was atributed to the polysaccharide. There was no change in the activities with the treatment of polymyxin B, which indicated that these plant polysaccharides were not contaminated by microbial lipopolysaccharides. Thus, their chemical properties and anti-complementary characteristics of the partially purified polysaccharides were studied. Some level of uronic acid and protein was contained in them, and their sugar composition was analysed by gas chromatography. Immunoelectrophoresis using anti-human C3 serum made it possible to observe the cleavage of C3 in sera by polysaccharides and to elucidate the mode of complement activation. In addition, some other results will be presented herein.