No infrastructure, no centralized administration and self-configuration are the main characteristics of MANETs. The primary motivation of MANET deployment is to increase portability, mobility and flexibility. However, this mobility causes an unpredictable change in topology and makes routing more difficult. Many routing algorithms have been proposed and tested over the last few years in order to provide an efficient routing in Ad Hoc networks. In this report we will show our conducted study with AODV (reactive), DSDV (proactive) and ZRP (hybrid) routing protocols. The performance of routing protocols have been evaluated carefully by analyzing the affects of changing network parameters such as, number of nodes, velocity, pause time, workload and flows on three performance metrics: packet delivery ratio, routing cost and average end- to- end delay. All the simulation work has been conducted in NS2. Our simulation results show that AODV gives better performance in all designed simulation models in terms of packets delivery ratio. DSDV shows the second best performance. Performance of ZRP is found average.