Strain IGC 4047 of the yeast L. starkeyi grew well with dextran as sole source of C and energy and was able to hydrolyze blue dextran and Sephadex G-100. The enzyme was partially purified by fractionated isopropanol precipitation from the extracellular fluid of cultures grown in a minimal medium with dextran. The enzyme preparation showed only 1 band by polyacrylamide gel electrophoresis. The enzyme had the following properties: MW, 23,000; optimum temperature and pH for activity, .apprx. 50.degree. C and pH 5.0, respectively; pH stability, pH 3.5-7.5; after 2 h at 50.degree. C and pH 5.0, 30% reduction in activity; isoelectric point, pI = 5.4; final products of dextran hydrolysis, isomaltooligosaccharides from glucose up to isomaltohexase, with high concentrations of isomaltose and isomaltotriose. These results suggest that the enzyme is an endodextranase.