Assuming that the existence of an ion-flow in the plasmavolume could strength the surface modifying effect, including its durability, a parallel plate reactor in reactive ion etching mode was employed to obtain surface modified PDMS with improved cellular interaction. The discharge power was varied at 100, 1200, and 2500 W to ensure varied ion-flow density. The changes in the surface topography were observed by SEM and AFM, and the Surface roughness was characterized by both: mean roughness, R-a, and root-mean-square, R-q. Time dependent water contact angle measurements were performed to control the durability of the hydrophilizing effect. Anisotropic etching, accompanied with decrease of the PDMS Surface roughness, was observed Lip to discharge power of 1200 W that turns in intense isotropic one, accompanied with a sharp increase of the surface roughness over 1200 W, most probably because of arise of reverse sputtered neutrals diffracting the main plasma Ar+ flow. Human fibroblasts were applied as in in vitro model to learn more about the initial cellular interaction of the modified surfaces and to identify the optimal treatment conditions. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 111: 2637-2646,2009