WiMAX technology, the commercialization of the evolving IEEE 802.16 standard, aims to solve the last-mile problem with broadband wireless access at the scale of metropolitan area networks. WiMAX has attracted significant attention and interest because of its wide transmission range, high transmission rate, and mobility support. However, to make WiMAX networks usable and reliable, several security issues must be addressed in the standard and its protocols. In this article, the authors give an introduction to the security protocols used in WiMAX networks and then discuss why these protocols are deficient in terms of anti-replay, efficiency, scalability, and forward and backward secrecy, as well as how they can be enhanced to address these issues for real applications.