Nowadays privacy and anonymity have become an increasing requirement in wireless networks. However, current mobile peer-to-peer architectures have not taken into account anonymity, especially the mutual anonymity between two nodes. In this paper, we propose a mutual anonymity protocol, called secret-sharing-based mutual anonymity protocol (SMA), for mobile P2P networks. Our simulation results show that SMA achieves mutual anonymity in mobile P2P networks with a low cryptography processing overhead.