Hyaluronic acid (HA) coated drug carriers (HCDCs) were successfully synthesized by chemical conjugation method for targeted delivery of doxorubicin (DOX) as a prototype anticancer drug to CD44 expressed human breast cancer cell. From XPS analysis, the HCDCs by conjugation methods demonstrated the superior HA fixation amount and colloidal stability compared with the nanoparticles by nanoprecipitation. The cytotoxicity of the HCDCs formulation accessed by the MTT assay against the higher CD44 expressed cell line (MDA-MB-231) and lower CD44 expressed cell line (ZR-75-1) human breast cancer cell lines demonstrated that the HCDCs formulation exhibited excellent tumoricidal effect and their affinity to cancer cells was predominant. The in vitro drug release profile of the HCDCs showed sustained release behavior and after 14 days, 80% of the encapsulated DOX was released due to a high release rate of DOX from HCDCs. We synthesized that HCDCs have therapeutic potentials of cancer as a target specific fashion by increasing the tumoricidal efficacy of targeted cancer cells while reducing their cytotoxicity of non-targeted cells to minimize the side effect. Biotechnol. Bioeng. 2008;99: 442–454. © 2007 Wiley Periodicals, Inc.