The pseudobioaffinity chromatography with L-histidines immobilized onto poly(ethylene-vinyl alcohol) hollow-fiber membranes was studied for a selective purification of anionic oligosaccharides. Oligoglucuronans with different degrees of polymerization and acetylation, prepared by an enzymatic degradation of bacterial polyglucuronic acid, were used as models. The adsorption and elution parameters were studied to optimise the selective adsorption. A better understanding of the physico-chemical phenomena governing this selectivity was attempted and a few hypotheses on the mechanism of selectivity are proposed.