Abstract: The invention relates to a medical instrument that can be inserted into a human or animal body. The medical instrument includes an instrument body having at least one poor electrically conducting rod-type body made of a matrix material and non-metallic filaments. The medical instrument is characterized in that the rod-shaped body is doped with X-ray marker particles, and the medical instrument includes an MR-marker, or the instrument body includes an immobilized active MR marker in the surface area.