- As parallel implementation of complex applications is becoming popular, the need for a high performance interprocessor communication system becomes imminent, especially in loosely coupled distributed-memory multiprocessor networks. An important factor in the efficiency of these networks is the effectiveness of the message-passing system which manages the data exchanges among the processors of the network. This paper presents the modeling and performance evaluation of a new Message-Passing System (MPS) for distributed multiprocessor networks without shared-memory and where the processors or Processing Elements (PEs) are connected to each other by point-to-point communication links. For maximum performance, the MPS manages the communication and the synchronization between the different tasks of an application by means of three approaches. One is an asynchronous send/receive approach which handles efficiently server like tasks, the second is a synchronous send/receive approach which handles efficiently streaming communication mode and the third is a virtual channel approach which minimizes the overhead of the synchronization mechanism, efficiently handling the burst mode of heavy communication between tasks. The developed models of the MPS approaches enable the determination of analytical expressions for different performances and a comparison between analytical and experimental performances reveals that the models predict the MPS performance with high accuracy. The MPS written in Parallel ANSI C, is studied on a mesh topology network of 16 transputers T800. The MPS performances for each approach are studied and presented in terms of communication latency, throughput, computation efficiency and memory consumption.