In multi-issue negotiations, autonomous agents can act cooperatively to benefit from mutually preferred agreements. However, empirical evidence suggests that they often fail to search for joint gains and end up with inefficient results. To address this problem, this paper proposes a novel mediated negotiation procedure to support the negotiation agents in reaching an efficient and fair agreement in bilateral multiissue negotiation. At each stage of negotiation, the mediator searches for the compromise direction based on a new EDD (Equal Directional Derivative) approach and computes the new tentative agreement. The numerical analysis presented in this paper demonstrates that the proposed approach not only guarantees Pareto efficiency, but also produces fairer improvements for two negotiating agents compared with other existing methods. Categories and Subject Descriptors I.2.11 [Distributed Artificial Intelligence]: Multiagent Systems; K.4.4 [Computers and Society]: Electronic Commerc...