Transformation-associated expression of Leb (Lewis antigen-b) or LeY in human colorectal carcinomas has been well described. To examine the expression of glycosphingolipids (GSLs) bearing Lewis-phenotypes in human gynecological carcinoma-derived cells, we determined the concentrations of all GSLs. Although neither Leb nor LeY was present in HEC-108 cells established from the poorly differentiated type of endometrial adenocarcinoma, other cell lines from moderately or well-differentiated types expressed either Leb or LeY, or both, at concentrations of 0.01 to 0.03 μg per mg of dry cells, which comprised 0.3 to 1.3% of the total GSLs. In the cervical and ovarian carcinoma-derived cell lines, Lewis phenotypes tended to be carried by nLc4Cer, which was accumulated in the cells without sialylation or fucosylation. These results indicated that expression of Leb- or LeY-phenotypes was strongly dependent on the metabolic ability to supply the precursor GSLs. Both Leb and LeY were successfully detected by monoclonal antibody MSN-1, which was a useful probe for the simultaneous detection of Leb and LeY. On application of MSN-1, either Leb or LeY was detected in tissues from patients with well- and moderately differentiated types of endometrial adenocarcinoma at concentrations of 0.01 to 0.04 μg per mg of dry tissues, but not in the tissues of poorly differentiated type. Normal endometria at the follicular and luteal phases also contained the antigens, but the concentrations and the frequency of antigen expression were lower than those in the well- and moderately differentiated types of endometrial adenocarcinoma.