OmniRPC is a Grid RPC system for parallel programming in a grid environment. In order to understand the performance characteristics of OmniRPC, we executed a synthetic benchmark program which varies the execution time in remote nodes and the amount of communication on several con.gurations of our grid environment. The result shows the performance of the application is improved if RPC data transmissions are less than 10 KB, the job time in remote nodes is more than 4 seconds, and RPCs are called more than 256 times. Our result also shows a small performance degradation when using the feature of communication multiplexing. We also measured the performance of the EP application from the NAS parallel benchmark suite. In EP, even if using SSH or the Globus GRAM as methods of agent invocation, both performances are almost the same. As a practical application, we parallelized the CONFLEX molecular con.rmation search program using OmniRPC. In the comparison of CONFLEX-G with the CONFLEX MPI version, CONFLEX-G achieves comparable efficiencies to the MPI version and increased speed by using two or more clusters.