Plasma polymerization of allylamine, acrylic acid, and an allylamine/acrylic acid mixture on Silastic(R) silicone rubber led to a strong increase in the silicone rubber's hydrophilicity and surface energy. Analysis of the deposited layer by X-ray photoelectron spectroscopy with 20degrees and 70degrees takeoff angles showed segregation of the atoms according to the depth and the incorporation of amino groups, oxygenated groups, and both. The endothelialization of untreated and treated samples was evaluated by the seeding and growth of aorta epithelial cells from pigs in cellular adherence (%), doubling time (in hours), and confluent density (10(4) cells /cm(2)). The best results were obtained with the allylamine/acrylic acid mixture treatment, which brought a biocompatibility to Silastic(R) similar to classic tissue culture on polystyrene plates. The interpretation was based on the presence of NH3+/CO2- microareas in the deposited layer. (C) 2003 Wiley Periodicals, Inc.