Abstract:WiMAX is a recent technology in wireless communication that is based on IEEE 802.16 standard.It is a Wireless Metropolitan Area Network. The WiMAX trademark was coined by WiMAX Forum.This Forum defines the precise content and scope of WiMAX technology through technical specification. WiMAX provides many advantages over previous technologies like high data rates, scalability, quality of service and security. WiMAX provides many security techniques but still it is vulnerable to various threats.This paper exposes those threats and their countermeasures.