Biodegradable polyesters such poly(lactic acid) and poly(lactic/glycolic acid) (PLGA) copolymers are preferred biomaterials and used among others as drug delivery systems, although their surface hydrophobicity limits their application. In this work, chemical modification of the PLGA surface was developed by coupling of either linear or starlike poly(ethylene glycol) (PEG) molecules via chemical bonds to the PLGA surface following amino functionalization as a first step to improve its biocompatibility. The chemical attachment was followed by detailed X-ray photoelectron spectroscopy (XPS) studies. It was shown that substantial modification can be achieved by linear PEG, but even higher surface coverage with hydrophilic groups can be obtained when the six-armed PEG is applied with the additional advantage of possible further functionalization via free amino groups available on the surface of the latter. As a final goal, a significant increase of water wettability together with reduced protein adsorption was achieved on PEG-coupled PLGA surfaces.