In this paper, we propose a practical scheme for privacy protection and authentication of medical images with the aid of EXIF metadata and associated records of the patients. By using watermarking, the goals mentioned above can be reached. Application for robust watermarking is one of the major branches in digital rights management (DRM) systems. With robust watermarking, it generally alters selected coefficients in the transform domain to accomplish the embedding process. We consider not only the image contents itself, but we also employ the EXIF metadata, which contains the patients' records and serves as the role of watermark, to be integrated into our scheme. By doing so, the false negative probability for obtaining the record can be reduced. Moreover, taking the information that the medical doctor recorded in the EXIF metadata into account, conventional watermarking techniques can be applied to medical images, and watermarked images with good quality can be produced. Even when the marked image has been intentionally modified, the original EXIF with selected information can mostly be recovered from the decoding process. Simulation results present the effectiveness of such an implementation.