In this paper, the authors present a comprehensive overview on Ad hoc networking by directional antennas. Use of Directional antennas can largely reduce the interference, increase the spatial reuse and due to their longer range they can have routes with fewer hop for two distant nodes. However the main problem of using directional antennas in Ad hoc networks is due to the dynamic nature of the network. Neighbor discovery, maintenance the track of moving neighbors, exploitation of the benefit of long range and directional MAC protocols are the most challenging issues. They present three Directional MAC protocols and two combinational protocols and system which give solutions to MAC and Neighbor discovery and compare the throughput of them with 802.11 with omni-directional antennas.