1. The red blood cells of sheep sensitized by polysaccharide of E. Coli and the hemagglutination recognized by anticoliserum of rabbit. 2. The ability of sensitizing by the polysaccharide is not weakened by 100°C. The red blood cells well sensitized in 37°C, but in case of the low temperature (under 5°C) or in acid solution, weak. 3. The hemagglutination by protein fraction of E. Coli can not recognized.