Peer-to-peer networks and mobile ad hoc networks (MANETs) share the same characteristics of self-organization, decentralization, and dynamic topology. Therefore, it is natural to apply peer-to-peer techniques to MANETs. A lookup protocol, one of the most important issues in a peer-to-peer computing, is an essential component for resource searching. In this paper, we propose interest-based bandwidth-efficient lookup protocols, simple lookup protocol and advanced lookup protocol, for mobile environments. A peer willing to search files broadcasts a query message with keywords relevant to its interests to its neighbors in the transmission range, and only those neighbors also interested in the query forward. Simulation results show that our protocols have higher success rate and raise the scalability and bandwidth efficiency comparing to the previous work. Besides, our protocols can avoid selfish behaviors, since the behavior of forwarding queries benefits not only the source node but also the forwarding node.