Fructan pentasaccharides were purified, in quantities suitable for use as substrates for enzyme assays, from Neosugar-p-(Meijj Seika Kaisha Ltd. Japan), tubers of Helianthus tuberosus L., L., and stems and leaf sheaths of Triticum aestivum L by a combination of gel-filtration and RP-HPLC. Fructan of higher molecular mass (mean DP = 30) was purified from Leaves of Lolium rigidum Gaud, that had been induced to accumulate fructan and characterized along; with the commercially available fructan from Cichorium intybus L. (Sigma, St Louis, USA) (mean DP = 33). The fructan pentasaccharide purified from H. tuberosus was found to contain exclusively 2, 1-linked fructose and terminal fructose and terminal glucose, and was identified as (1, 1, 1)-kestopentatise. The fructan pentasaccharide purified from Neosugar-P also contained (1,1,1)-kestopentaose. although the presence of fructan Klinked glucose and 1 % 2, 6-linked fructose indicated that a small proportion of other kestopentaoses were present, The fructan pentasaccharide purified from T aestivum consisted of almost exclusively 2,6-linked fructose and terminal glucose and terminal fructose and was considered to contain predominantly (6,6,6)-kestopentaose. The presence of 1 % 2,1,6)-linked fructose indicated the sample also contained a small proportion of branched kestopentanse. The high molecular mass fructan from C. intybus was found to comprise linear molecules containing only 2,1-linked fructose, terminal glucose and terminal fructose- High molecular mass fructan from L. rigidum contained predominantly 2. h-linked fructose, had predominantly internal glucose, indicated by 2 %, 1.6-linked glucose, low levels of branching, indicated 2 % 2,1,6-linked fructose residues; and 1% of the residues were 2,1 -linked fructose.