Fructo-oligosaccharide represent one of the major classes of bifidogenic oligosaccharides in term of their production volume, because of their favorable functional properties. These include: a/ improving the intestinal microflora; b/ relieving the constipation; c/ decreasing the total cholesterol and lipid in serum; d/ the promotion of animal growth and e/ as low calorie non-cariogenic sweeteners (Chen and Liu, 1996). FOS are manufactured by two differing processes which result in slightly different end products--using either microbial fructosyl transferase (EC 2.4.1.9) or beta-fructofuranosidase (EC 3.2.1.26) with high transfructosylation activity. The present study reports on the biosynthesis of an extracellular inulinase by yeasts from genus Kluyveromyces. The strains were isolated from different dairy products. Some of the studied strains produced large amounts of extracellular inulinase activity when grown on inulin ar sucrose as carbon source. In addition, the effect of C/N ratio on the production of extracellular inulinase was studied. Thin layer chromatography showed that inulinase from K. species 19 was capable of hydrolyzing inulin, releasing monosaccharides and oligosaccharides.