A novel process for producing isomaltose and uses thereof and comprising the steps of contacting saccharides, which have a glucose polymerization degree of at least two and .alpha.-1,4 glucosidic linkage as a linkage at the non-reducing end, with an .alpha.-isomaltosylglucosaccharide-forming enzyme, in the presence or the absence of .alpha.-isomaltosyl-transferring enzyme to form a-isomaltosylglucosaccharides, which have a glucose polymerization degree of at least three, .alpha.-1,6 glucosidic linkage as a linkage at the non-reducing end, and .alpha.-1,4 glucosidic linkage as a linkage other than the non-reducing end, and/or to form cyclo{.fwdarw.6)-.alpha.-D-glucopyranosyl-(1.fwdarw.3)-.alpha.-D-glucopyr- anosyl-(1.fwdarw.6)-.alpha.-D-glucopyranosyl-(1.fwdarw.3)-.alpha.-D-glucop- yranosyl-(1.fwdarw.}; contacting the saccharides so formed with isomaltose-releasing enzyme to release isomaltose; and collecting the released isomaltose; and uses thereof.