Amorphous hydrogenated carbon films containing different amounts of fluorine and silicon have been deposited by plasma activated chemical vapor deposition in a stainless steel high vacuum system, using different mixtures of acetylene and either trifluoromethane or tetramethylsilane. Film composition and the different chemical states present have been characterized by X-ray photoelectron spectroscopy. Cell culture tests with fibroblasts revealed a good surface biocompatibility by means of morphological behavior, but no dependence on the Si or F content in the a-C:H films could be seen. All cells showed good spreading on the surface. Within 2 days confluent cell layers were observed.