In an ad hoc network, mobile nodes communicate with each other using multi-hop wireless links. There is no stationary infrastructure such as base stations. The routing protocol must be able to keep up with the high degree of node mobility that often changes the network topology drastically and unpredictably. Most of the on demand routing protocols for Manets namely AODV and DSR perform well with uniform output under low network load, mobility, traffic sources. The objective of the proposed work is to evaluate the performances of each of these protocols under large number of traffic sources, greater mobility with lesser pause time and varying offered load. Also the metrics taken into account are: Packet Size /average throughput of generating packets, Packet size / average simulation end to end delay, packet send time at source node / end-to-end delay. On the basis of the obtained results the performances of the above-mentioned on demand routing protocols for Manets is compared using network simulator-2 (NS2).