The synthesis of side-chain-functionalized polyaspartamides as potential carrier polymers for medicinal agents is described. The nucleophilic ring opening in poly-D,L-succinimide, mediated by O,O’-bis(2-aminopropyl)poly(ethylene oxide) (nominal molecular mass is 600) and ethanolamine under carefully controlled experimental conditions leads to the formation of aspartamide polymers bearing hydrosolubilizing hydroxyethyl side groups in addition to variable proportions of poly(ethylene oxide) (PEO) side chains terminated with primary amino groups. The side chain terminals represent functionalities for drug binding, whereas the PEO constituents contribute to overall hydrophilicity and biocompatibility of the carriers and to enhance their biomedical performance by imparting resistance to protein binding and increasing central circulation lifetime. The water soluble polymeric products are isolated by dialysis (molecular mass cutoff : 25,000) and freeze-drying in typical yields of 40-60%, with inherent viscosities in the range of 10-18 mL g(-1). Polymer compositions are determined by H-1 NMR spectroscopy and microanalysis. A selected carrier is modified by N-acylation with 4-ferrocenylbutanoic acid as a model drug, giving a ferrocene-containing, water-soluble conjugate, thus demonstrating the accessibility of the terminal amino groups on the PEO side chains to acylating agents and other potential reactants.