A method for reshaping, in particular for straightening, keratin-containing fibers, in particular human hair, includes (i) applying a pretreatment agent including amino-functional silicone(s) with terminal hydroxyl group(s) onto the keratinic fibers and left there, (ii) optionally drying fibers, (iii) treating the fibers in the moist or dried state with a reshaping agent which, relative to the weight of the reshaping agent, includes 0.05 to 20 wt. % of guanidine and/or guanidinium salt(s), (iv) optionally straightening the fibers with a comb or a brush during the reshaping treatment, (v) shampooing the fibers with a shampoo which has a pH of 2.5 to 6.5, followed by rinsing and neutralizing the fibers, and (vi) optionally subsequently additionally mechanically deforming the fibers with exposure to heat. The methods distinctly minimizes the negative consequences of reshaping, in particular electrostatic charging and hydrophilization of the hair.