Monoclonal antibodies (MAbs) directed to Lewis(x) (Le(x)) and related carbohydrate sequences have been invaluable in anticipating biological roles for these oligosaccharides by detecting the remarkable changes that occur in their expression from the earliest stages of embryogenesis, through development and sequential stages of cell differentiation and maturation. A notable impact has been in the molecular dissection of ligand-receptor interactions in key cell adhesion events at the initial stages of leukocyte recruitment in inflammation, and almost certainly in the metastasis of epithelial tumours. Antibodies that recognise Le(x) and the 3'-sialyl forms were observed to identify leukocyte subsets; these were subsequently found to match those recognized by the leukocyte-endothelium adhesion molecules, the E- and P-selectins. We now describe a MAb (rat hybridoma MIN/3/60) raised to 3'-sulpho-Le(x), a carbohydrate sequence which, in vitro, is bound not only by the E-, L-, and P-selectins, but also by the cysteine-rich domain of the macrophage endocytosis receptor. We observe that MIN/3/60 is bispecific, however; it binds 3'-sulpho-Le(a) as well as 3'-sulpho-Le(x). Nevertheless, our exploratory studies reveal that it may be a useful histochemical reagent when used in conjunction with a monospecific antibody to 3'-sulpho-Le(a). The MIN/3/60 antibody reveals a sub-population of epithelial glycans in the crypts of Lieberkühn in normal human colon.