Mobile ad hoc network (MANET) is a group of portable hosts without the required intrusion of any existing arrangement or centralized access point such as a base station. Due to the major characteristic of MANETs i.e. vigorous topology and lack of centralized management security, MANETs are vulnerable to attacks. Black hole attack is one of the possible attacks in MANET. A black hole attack is network layer attack in which the mischievous node misleadingly advertises to the source node that it is having shortest path to the destination and actually it does not have and drops the packets and as a result the destination node never receives that packet. In this paper, we study the behavior of AODV (Ad hoc on Demand Distance Vector Routing Protocol) with and without black hole nodes on various parameters like End to End delay, Packet delivery ratio, Throughput and Routing Load. All the parameters are analyzed using NS2 simulator.