The security of multimedia data is important for multimedia commerce. The encryption algorithms with high security, such as DES and IDEA, may not be suitable for multimedia applications because of large data sizes and real time constraint. This paper proposes a fast encryption algorithm for high throughput multimedia data, called FEA-M. FEA-M is based on Boolean matrix theory. The plaintext and the ciphertext are 64 ´ 64 Boolean matrices while the secret key is also an 64 ´ 64 matrix. The structure of FEA-M is chosen to provide confusion and diffusion and to facilitate both hardware and software implementation.