Eavesdropping is an important threat in the context of mobile ad-hoc networks due to the use of open air as the transmission medium. As a consequence, some works trying to prevent this threat have been proposed. Some of these proposals focus on the use of anonymous routing protocols. In this paper we analyze two of the most popular: ANODR and MASK. We evaluate their performance through simulation in terms of throughput and routing overhead in order to measure the cost of providing anonymity. Simulation results show that these anonymous routing protocols reduce performance to inefficient levels.