(Figure Presented) Polymerie micelles comprising a hydrogen-bonding core were formed from block copolymers with pendant urea groups and explored as drug delivery vehicles. The amphiphilic block copolymers were synthesized by organocatalytic ring opening polymerization (ROP) of ureafunctionalized cyclic carbonates from a polyethylene glycol) macroinitiator. The urea functionality was incorporated because its ability to increase the hydrophobic core's affinity toward polar organic compounds through intermolecular hydrogen bonding. Doxorubicin (DOX), a lipophilic anticancer drug with hydrogen-bonding functionalities, was systematically incorporated into the micelle's hydrophobic interior via hydrogen bonding to the functionalized monomers. Micelles employing urea groups were found to more efficiently interact with DOX thus allowing increased drug loading capacity while maintaining a desirable micellular size. More importantly, while DOX-loaded micelles were shown to kill HepG2 human liver carcinoma cell lines efficiently, all of the polymers were non-cytotoxic. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.