Novel multidrug nanoparticles were self-assembled from the random copolymer containing cytarabine and fluorodeoxyuridine. The multidrug copolymer carrying 28.7 wt.% of cytarabine and 29.1 wt.% of fluorodeoxyuridine was prepared by radical polymerization combined with enzymatic selective transesterification. Homopolymers of the two drugs were also synthesized by the same method. And the polymers were characterized by FTIR, H-1 NMR, and gel permeation chromatography (GPC). Self-assembly of the multidrug copolymer was verified by UV-vis and fluorescence spectroscopy. The morphology of nanoparticles formed from the copolymer was investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS), which indicated that the nanoparticles were regular spheres with a diameter of 133 +/- 28 nm. In vitro drug release studies illustrated that the two synergistic anticancer agents could be simultaneously released from the multidrug nanoparticles. (C) 2010 Elsevier Inc. All rights reserved.