An arabinoxyloglucan (amyloid) isolated from bright tobacco (Nicotiana tubacum, L. cv., Delhi 76) consists of L-arabinose, D-xylose, and D-glucose residues in the molar ratios 1:2.2:6.8. Sedimentation data indicate that the polysaccharide is homogeneous. The methylation analysis data show a statistical unit of 20 sugar residues with 5 terminal, non-reducing end-groups (3 D-xylosyl and 2 L-arabinosyl). There are 5 residues of D-glucose involved in branching through positions 4 and 6. The remaining 10 non-terminal residues consist of two (1→2)-linked D-xylosyl residues and eight (1→4)-linked D-glucosyl residues. The proposed statistical unit accords with the periodate-oxidation results. The formation of ~0.1 mol each of 2,3,4,6-tetra-O-methyl- and 2,3,4-tri-O-methyl-D-glucose suggests that an average unit may contain ~200 sugar residues. Several xyloglucans (amyloids) from a variety of sources have been characterised. A xylan from the stalk and a 4-O-methylglucuronoxylan and an arabinoxyloglucan from the midrib of the leaves of uncured, greenhouse, bright tobacco have been isolated and characterised, and the extracellular polysaccharides from suspension-cultured cells of tobacco have also been studied. We have reported the isolation and characterisation of an Amadori compound, the low-molecular-weight carbohydrates, and the water-soluble pectic polysaccharide from the cured-leaf laminae of tobacco, and we now describe further work on the sodium hydroxide-soluble polysaccharide fraction.