Polyethylene (PE) was modified by an Ar plasma. The plasma-activated PE surface was grafted with poly(ethylene glycol) (PEG, molecular weight 300 and 20 000). The depth profiles of the oxygen in the modified PE samples were determined using Rutherford Backscattering Spectroscopy (RBS). The changes in the surface wettability were examined by goniometry, and Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology. The modified PE samples were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation was studied. The plasma treatment and the subsequent PEG grafting leads to dramatic changes in the PE surface morphology, roughness and wettability. The PEG grafting of the plasma-treated PE does not increase VSMC adhesion but it results in dramatic increase of VSMC proliferation. (C) Koninklijke Brill NV, Leiden, 2010