A Mobile Ad hoc NETwork (MANET) consists of mobile wireless nodes. In MANET nodes are self-motivated topologies can randomly change their geographic locations. Wireless networks are susceptible to many attacks, including an attack known as the wormhole attack. On occurrence of wormhole can cause a significant breakdown in communication across a wireless network. This paper explores and compares the effect of wormhole attacks on the performance of on demand routing protocols in Mobile Ad hoc NETwork (MANET). The evaluation has been done by studying and comparing end to end delay, packet delivery ratio and throughput for wormhole attack and without wormhole attack.