Method for smoothing fibers containing keratin, in particular human hair. Fibers are subjected to a thermal treatment and to a treatment with an agent containing at least one conditioning compound selected from cationic polymers, quaternary ammonium compounds, silicones and protein hydrolyzates. The invention also relates to the use of an agent containing at least one of the conditioning compounds concerned in said method for smoothing fibers containing keratin. The inventive method achieves an excellent, uniform smoothing of the fibers, which are also conditioned.
