A method and apparatus for selecting a service path of a Mobile Station (MS) in a relay communication system. The method includes periodically transmitting, by a Base Station (BS), a preamble (or pilot) signal to the MS and Relay Stations (RSs) existing within a cell; measuring, by the RSs, a Signal-to-Interference and Noise Ratio (SINR) of a BS-RS link, and transmitting the measured SINR and the preamble (or pilot) signal to the MS; by the MS, measuring an SINR of each link using signals received from the BS and the RSs; and by the MS, computing throughput in consideration of the SINR of each link and frequency resources reused in the RSs existing within the cell, and selecting a service path having the highest throughput.