We have developed a direct conjugation method of RGD (Arg-Gly-Asp) into polylactide (PLA) using co-solvent system, which showed high reaction yield compared to one solvent system presumably due to good solubility of reactants. First, hydroxyl groups at the end of PLA were changed into carboxyl acid by ring opening reaction of succinic anhydride. For a coupling reaction with high solubility, RGD was dissolved in water and then PLA in dioxane was added into RGD solution in the presence of 1-(3-dimenthylaminopropyl)3-ethylcarbodiimide hydrochloride (EDC). The conjugation of RGD was confirmed by 1H-NMR, GPC and elementary analysis. The RGD conjugated PLA (RGD-PLA) on poly(lactide-co-glycolide) (PLGA) film significantly increased the number of attached cells compared to PLGA without RGD-PLA, while it did not change static contact angle of PLGA. This result demonstrated this conjugation method would be a useful tool to increase cell affinity of biomaterials without change in hydrophilic/hydrophobic property for tissue engineering applications.