Ad hoc networks are mobile devices that have no fixed infrastructure. There are no fixed routers-instead each node acts as router and forwards traffic from other nodes. MANET (Mobile Ad-Hoc Networks) is a type of ad-hoc network with rapidly changing topology. Since the nodes in a MANET are highly mobile, the topology changes frequently and the nodes are dynamically connected in an arbitrary manner. In order to facilitate communication with the network, a routing protocol is used to discover the routes between nodes. Efficient routing of packets is a primary MANET challenge. Today , their exist various routing protocols for this environment. This paper is the study of comparison of the performance of some of the protocols and the evaluation is done by using GloMoSim Simulator.