In traditional medicine fresh pressed juice of white cabbage leaves is used in the treatment of many diseases in which immunity disorders are involved: diabetes mellitus, rheumatism, gastric ulcer, cirrhosis, cancer. The efficiency of fresh cabbage juice might be due to an immunomodulatory activity. Polysaccharides are hydrosoluble compounds for which there have been pointed out immunomodulatory effects in recent years. This is the reason why a raw polysaccharide was isolated from the fresh pressed juice of white cabbage leaves. The raw polysaccharide was purified and submitted to a chemical study based on analysis of proteic component (quantification of total nitrogen, total proteins and soluble proteins) and analysis of polysaccharides component (isolation and characterization of main polysaccharides fractions, identification of main sugar components, quantification of uronic acids). Further in vitro studies will evaluate the immunomodulatory capacity of this polysaccharide.