In this paper, we propose iTrust, a probabilistic misbehavior detection scheme to achieve efficient trust establishment in DTNs. we propose a general misbehavior detection framework based on a series of newly introduced data forwarding evidences. The proposed evidence framework could not only detect various misbehaviors but also be compatible to various routing protocols. We introduce a probabilistic misbehavior detection scheme by adopting the inspection game. A detailed game theoretical analysis will demonstrate that the cost of misbehavior detection could be significantly reduced without compromising the detection performance. We also discuss how to correlate a user’s reputation (or trust level) to the detection probability, which is expected to further reduce the detection probability. The extensive analysis and simulation results demonstrate the effectiveness and efficiency of the proposed scheme.