Abstract: A passive transponder may be encoded with a number or code of up to 64 binary bits and then mounted to virtually any prosthesis implanted in a human, such as a breast implant. After implantation, the transponder's code may be conveniently read with a hand held electromagnetic reader which may merely be brought within proximity of the transponder. The encoded transponder may thus be read in a non-invasive procedure and without the use of any sophisticated or potentially harmful medical equipment or technology such as X-ray. The information encoded in the transponder may correspond to patient demographics and implant data to aid in tracking the implant's manufacturer and use for medical as well as legal reasons.