—Popularity of group-oriented applications motivates research on security and privacy protection for group communications. A number of group key agreement protocols exploiting ID-based cryptosystem have been proposed for this objective. Though bearing beneficial features like reduced management cost, private key delegation from ID-based cryptosystem, they have not taken into account privacy issues during group communication. In wireless networks, the privacy problem becomes more crucial and urgent for mobile users due to the open nature of radio media. In this paper, we proposed an anonymous IDbased group key agreement protocol for wireless networks. Based on ID-based cryptosystem, our protocol not only benefits from the desirable features of ID-based cryptosystem, but also provides privacy protection for mobile users. More important, in the proposed protocol, the computation cost for each group member is largely reduced to meet the computation capability restriction of mobile devi...