There is provided a wind turbine rotor blade comprising a rotor blade casing, and a lightning protection system having at least one lightning protection cable and a lighting protection cable holder. The lighting protection cable holder is fixed in or to the inside of the rotor blade casing. The lighting protection conductor holder has a first part and a second part. The first part is fixed to an inside of the rotor blade casing and has a receiving portion for receiving the lighting protection cable. The second part is in the form of a cover or covering means and is placed over the receiving portion. The first and second parts each have a radar-absorbing core or a radar-absorbing layer and an electrically insulating material which surrounds the radar-absorbing core or the radar-absorbing layer.