In order to develop new physiologically active polysaccharides from persimmon leaves, two different crude polysaccharides were prepared using hot water (PLW-0) and pectinase digestion (PLE-0) and their immuno-stimulating activities were estimated. PLW-0 and PLE-0 showed similar sugar compositions with 15 different sugars, including rarely observed sugars in general polysaccharides such as 2-O-methyl-fucose, 2-O-methyl-xylose, apiose, aceric acid, 3 deoxy-D-manno-2-octulosonic acid, and 3-deoxy-D-lyxo-2-heptulosaric acid, but the uronic acid content of PLE-0 was lower than that of PLW-0 caused by pectinase treatment. Both PLW-0 and PLE-0 showed potent anti-complementary activity in a dose dependent manner which was similar to a known immuno-stimulating polysaccharide, PSK, from Coriolus versicolor. The activity of PLE-0 at a low concentration (100 ㎍/㎖) was higher than that of PLW-0. In an in vitro cytotoxicity analysis, PLW-0 and PLE-0 (up to 1, 000 ㎍/㎖) did not affect the growth of peritoneal macrophages and Colon 26-M3.1 carcinoma cells. In contrast, they enhanced lymphocyte proliferation activity. Peritoneal macrophages stimulated with PLW-0 and PLE-0 produced various cytokines, such as IL-6 and IL-12. However, PLE-0 was more effective on the cytokine production. Intravenous administration of PLW-0 and PLE-0 significantly augmented natural killer (NK) cell cytotoxicity against Yac-1 tumor cells 3 days after the treatment of polysaccharide fractions. But NK cells obtained from the PLE-treated group showed higher tumoricidal activity even at a low dose of 40 ㎍/mouse. In experimental lung metastasis of Colon 26-M3.1 carcinoma cells, prophylactic administration of PLW-0 and PLE-0 significantly inhibited lung metastasis in a dose-dependent manner and PLE-0 was more effective on the inhibition of cancer metasasis. The results lead us to conclude that the pectinase treated process is indispensable to preparing polysaccharides with higher immune-stimulating activity from persimmon leaves.