Background α 1,2Fucosylation of glycoconjugates has been previously demonstrated to be tumor specific in human colorectal tissues and to be associated with resistance of tumor cells against anticancer treatments.By using a novel monoclonal antibody (YB-2), aberrant expression of H type 2 (Fucα 1,2Gal β 1,4GlcNAc), Leb (Fucα 1, 2Gal β 1, 3, Fuc α 1,4, GlcNAc) and Y (Fucα1,2Galβ1, 4, Fucα1, 3, GlcNAc) antigens was identified in colorectal tumor tissues despite the complete absence of ABH antigens in their normal tissues (Glycobiology, 12:545-553, 2002).Methods Immunohistochemieal analyses of colorectal cancer tissues (74 specimens) were performed with a newly established mouse monoclonal antibody, YB-3 specifically recognizing H disaccharide (Fucα1, 2Galβ) structures, and anti-A, anti-B, YB-2 and anti-sialy1 Lewis X (SLX, NeuAc α2,3Galβ1,4, Fuc α1,3, GlcNAc) antibodies, together with measuring glycosyltransferase activities involved in the synthesis ABH antigens in the same tissues.Results With the aid of YB-3 monoclonal antibody, colorectal tumors, particularly tumors in the distal large intestine and the rectum, could be detected with high sensitivity (74.3%) and specificity (100%).Immtmohistochemical and enzymatic analyses of colorectal tissues showed that once α 1,2fucosylation had proceeded in tumor tissues, blood group A or B antigen was also synthesized in approximately half of the tissues of blood group A or B type, but never in their normal tissues.A significant correlation of survival rate with immunostaining of tissues was found only by YB-3 antibody but not by anti-A, anti-B or anti-SLX antibody.Conclusion As a predictor of postoperative prognosis of patients with colorectal cancer, immunodetection of α1,2fucosylated antigens with the YB-3 antibody could be superior to SLX, blood group A or B antigen in colorectal tumor tissues.