A method for producing a bioactive surface on an endoprosthesis, or on the balloon (3) of a balloon catheter (1) is described, wherein the surface (15) of the endoprosthesis, or the surface (4) of the balloon (3) is softened. The surface (15) of the endoprosthesis, or the surface (4) of the balloon (3) is moistened with a solution (6) of an active ingredient (7), and the solvent (8) is separated from the active ingredient (7). In addition, a balloon (3) of a balloon catheter (1) is disclosed, which comprises an uncoated surface (4), wherein an unencapsulated active ingredient (7) is embedded at least partially into the material of the surface (4). Furthermore, a balloon catheter (1) is described, which comprises a balloon (3) according to the invention. In addition, an endoprosthesis, particularly a polymer stent is described, which comprises an uncoated surface (15), wherein an active ingredient (7) is embedded at least partially into the material of the surface (15).
