Due to the rapid development of application for medical images in recent years, the security of medical images becomes more vital. In this paper, a fragile watermarking scheme for medical images is proposed. The proposed scheme first divides the whole medical image into ROI (Regions of Interest) and RONI (Regions of Non-interest). Then the JPEG-LS algorithm is applied to ROI to get the compressed data which will be embedded into the whole medical image. And then, image encryption methods are used to assure the invisibility of the medical image. At last, a POB number system enhances the security of the scheme. With the use of the scheme in this paper, we can judge whether the medical image is tampered or not, and can also recover the original medical images in specific conditions without any loss. Moreover, if the medical image is tampered, we can also localize the tampered regions. Experimental results show that the suggested scheme achieves a better performance on security, invisibility and robustness in comparison to the state-of-the-art methods for medical images.