A cosmetic agent for dyeing keratinous fibers, especially human hair, includes at least one specific protein-siloxane polymer and at least one oxidation dye precursor and/or a direct dye, where the use of the at least one protein-siloxane polymer leads to improved care of the keratinous fibers. A corresponding packaging unit (kit of parts) and a method for dyeing keratinous fibers include the cosmetic agent. Lastly, the cosmetic agent is used to care for keratinous fibers with an enhanced care effect.
