Medical imaging requires great integrity of content since any change in the image even in a slight amount might affect the diagnosis. Semi-fragile watermarking could be the best technique to provide an efficient image authentication tool for medical images. In this paper, we propose a semi-fragile watermarking technique for the tamper proofing of still images that can tolerate JPEG lossy compression to a predetermined lowest quality factor and rejects any replacement process. We also present comparison performance for the proposed algorithm to eight other common techniques.