The invention relates to a method for producing a bioactive surface on the balloon (3) of a balloon catheter (1). According to said method, the surface of the balloon (3) is at least partially wetted with a first solution of an active substance (8) and the section of the surface of the balloon (3) wetted with the first solution of an active substance (8) is then wetted with a second, saturated solution of the active substance (28). The invention further relates to a balloon (3) of a balloon catheter (1) the surface of which is at least partially coated with an active substance (11), the coating (11) being homogeneous and brittle in the entire coated region.