Abstract: A radiolucent breast implant is comprised of a silicon envelope filled with any biocompatible triglyceride such as peanut oil or sunflower seed oil, or any other material having an effective atomic number of 5.9 which is the effective atomic number of fat, the major component of a human breast. Such a breast implant is radiolucent in that it duplicates the photoelectric interaction of fat which is the major effect producing subject contrast at low radiation levels as used in mammography. A radiolucent breast implant dramatically improves the usefullness of mammography in detecting tumors in patients having breast implants and may also result in a lower radiation dose for each examination.