This paper presents a directional routing approach for multihop ad-hoc networks, which has been applied to two on-demand routing protocols: namely Dynamic Source Routing (DRS) and Ad Hoc On-Demand Distance Vector Routing (AODV). Both DSR-based and AODV-based directional routing protocols are designed to balance the trade-off between co-channel interferences from nodes hops away, and the total power consumed by all the nodes. In order to select the best route, three metrics are considered in the route discovery process. They consist of hop count, power budget, and overlaps between adjacent beams. By exploiting the direction of directional antennas, both routing protocols are capable of reducing overlaps between beams of the nodes along the route, thus eliminating interference. Arbitrary networks and random networks are considered in our simulations. The results show considerable performance gains for transmission of real-time traffic over ad hoc networks.