To improve the specific accumulation in tumor sites and aqueous solubility of atRA, the core-shell type of folate-PEG-g-PEI/atRA nanoparticles were prepared by complexation between cationic PEI segments in the copolymers and anionic charged atRA, and then characterized by 1HNMR, ELS, XRD, and TEM. In vitro atRA release from the nanoparticles was investigated as a function of drug content in sink condition. Cytotocicity of atRA against HepG2, KB cell lines were also evaluated by MTT assay. The lower the drug content, the faster atRA release. atRA incorporated in folate-PEG-g-PEI/atRA nanoparticles showed much higher cytotoxic effect compared with atRA itself.