Abstract: The present invention relates to a method for improving the biocompatibility of a surface, in particular a solid body surface, as well as a device, for example an implant, sensor or cell culture vessel, which is brought in contact with biological systems with a biocompatible surface. To improve the biocompatibility of surfaces, in particular in relation to cell cultures and tissues, in a simple way and for a plurality of different surfaces, the surface is meant to be brought in contact with reactive radicals according to the invention. The device according to the invention has a biocompatible surface that has been treated pursuant to the method according to the invention.