Cell adhesion mediated by E-selectin and its carbohydrate ligands, Le(a) and Le(x), plays an important role in cancer metastasis. We determined soluble E-selectin concentration in the sera of patients with cancers using double determinant sandwich assay. The results indicated that the patients with metastatic colon cancers had significantly higher serum E-selectin concentration than the patients having no metastatic lesion. The highest frequency of metastasis was obtained in Le(a) HIGH E-selectinHIGH patients (80%), while the frequency was quite low in Le(a) LOW E-selectinLOW patients (17%). Expression of E-selectin, as well as its carbohydrate ligands, is suggested to be a risk factor for the metastasis of epithelial cancers. Soluble E-selectin-carbohydrate complex was also detected in the sera of patients, and the frequency was especially high in Le(a) HIGH E-selectinHIGH patients.