The content, chemical composition and structure, some physicochemical properties and fermentation characteristics of dietary fibres from Palmaria palmata (dulse) were studied. The marine red algae contains 33.2-33.5% total dietary fibres measured on a dry weight basis using conditions simulating the gastric and intestinal environment (pH, temperature, ionic strength and time of incubation) and measured by an enzymatic/gravimetric method, respectively. The yield of soluble fibres by the simulated digestive tract conditions was lower (12.2%) than by the enzymatic/gravimetric method (18-9%). All soluble fibre fractions consisted of linear/3-1,4//31,3 mixed linked xylans containing similar amounts of 1,4 linkages (70.5-80.2%). The insoluble fibres contained essentially 1,4 linked xylans with some 1,3 linked xylose and a small amount of 1,4-1inked glucose (cellulose). Low intrinsic viscosities were measured from the soluble fibres (49.4-97.0 ml g 1) and water holding capacities of dry dulse particles of 4.3 and 4.7 g g-l were measured in buffer at pH 3.0 and 7.3, respectively. Soluble fibres are fermented within 6 h by human faecal bacteria into short chain fatty acids.