Abstract Water-unextractable wheat flour arabinoxylans were degraded with purified endo-(1→4)-β- d -xylanases and a (1→4)-β- d -arabinoxylan arabinofuranohydrolase from Aspergillus awamori in order to elucidate their structural features. The arabinoxylan fragments obtained were characterized and quantified using Bio-Gel P-2 chromatography in combination with high-performance anion-exchange chromatography. A model is proposed, based on the results obtained, in which arabinoxylans are envisaged as containing highly-branched regions, mostly consisting of tetrameric repeating units of unsubstituted and a double arabinofuranosylated xylose residue, interlinked with less-branched regions, which include subregions containing up to seven contiguous unsubstituted xylose residues. The highly-branched regions are enriched in both O -2,3 disubstituted, as well as O -2 monosubstituted, xylose residues. The latter are absent in the less-branched regions. Variation in arabinose/xylose ratio between different arabinoxylan populations is due to variation in the relative proportion, as well as the composition, of the less-branched regions. In general, water-unextractable arabinoxylans are degraded by the purified xylanases to a lesser extent than water-extractable arabinoxylans with similar arabinose/xylose ratios and glycosidic linkage compositions.