Drug delivery vectors for sustained release include a variety of polymeric constituents, both natural and synthetic. Among synthetic polymers several linear block copolymer systems have been explored for use as drug delivery vectors. Release of the pharmaceutical agent is affected by the degradation characteristics and/or by the swelling of the polymer. The goal of this study is to evaluate the degradation behavior of branched polyethylene oxide polylactide polyether ester as a drug delivery vector. Three samples of a star polyethylene oxide/polylactide copolymer with differing polylactide chain lengths were evaluated by characterizing the thermal properties of the neat polymer and in vitro degradation behavior. The thermal and morphological properties were examined by DSC, TGA and XRD. The in vitro polymeric micelle samples were observed over time by UV-vis, TEM and fluorescence. The four star PEO-PLA polymers have exceptional amphiphilic characteristics, which enable their use for a variety of applications. The polymers are thermally stable at biological conditions. In addition, the star polymers have shorter degradation times as compared to previously reported linear PLA and PEG-PLA copolymers, suggesting use as a short-term drug release agent. The four star PEO/PLA copolymer may be an excellent candidate for drug delivery applications. (c) 2005 Elsevier Ltd. All rights reserved.