For a proper fractionation of dextran, using the liquid-liquid two phase system water - non-solvent - dextran, the selection of the non-solvent is very important. Therefore, in this work the non-solvent isopropanol has been compared to ethanol with respect to the selectivity for a fractionation and to the required amount of non-solvent. It is shown that the influence of the concentration of ethanol and isopropanol in the total system on the molecular mass distribution of the dextran in both liquid phases is quite similar, but for getting the same result of a fractionation more ethanol than isopropanol is required.