In continuation of previous investigations of aspartamide-type polymers as drug carriers, polyaspartamides featuring hydrosolubilizing poly(alkylene oxide) side chains in addition to ethylenediamine side-group functions as potential drug-binding sites are synthesized from poly-D,L-succinimide by successive aminolytic ring-opening steps. Yields are in the range of 45-55%. Depending on selected feed ratios, the target polymers contain both the poly(alkylene oxide) and the ethylenediamine groups in systematically varied proportions. Compositions are determined microanalytically and from relative band intensities of the H-1-NMR spectra. The polymers dissolve smoothly and completely in aqueous media and thus fulfill the major design requirement of water solubility.