Abstract: The invention relates to a water-soluble, haemolytically inactive dextran fatty carboxylate with amphiphilic properties made from a dextran with an average molecular weight of 5,000 to 100,000 and a C.sub.10 to C.sub.14 fatty acid, preferably a C.sub.12 fatty acid, wherein the average degree of substitution is between 0.005 and 0.15 and is adjusted, depending on the average molecular weight of the dextran fatty carboxylate and the chain-length of the fatty acid used, in such a way that the dextran fatty carboxylate is soluble in water at room temperature, a process for its preparation and pharmaceutical or cosmetic preparations which contain it as solubilizer.