Abstract: Multimedia authentication is a problem posed to the world along with the development of Internet recently. Similar to message authentication, multimedia authentication is used to authenticate the source and to detect manipulation. This could be achieved by cryptographic digital signature. However, digital signature has some disadvantages to this end. Fragile watermark renders itself useful in this domain. There exist several fragile watermark schemes in the literature and all have their own cons and pros. After a successful analysis of the fragile watermark scheme presented by Marvel et al. , a new fragile watermark scheme robust to DCT-based compression is presented,which is an extension of and much safer than the one of Marvel et al. . Experiments show that a digital watermark scheme which use pixel values or significant bits of pixel values as input of MAC could not resist DCT-based compression.