An adaptive relay method in a communication system is provided to determine one of various relay modes for the maximum throughput, thereby improving the throughput of the system. An adaptive relay method in a communication comprises the following steps of: acquiring a downlink channel status between a BS(Base Station) and an MS(Mobile Station), a downlink channel status between a RS(Relay Station) and the MS, and a downlink channel status between the BS and the RS(902); determining an AMC(Adaptive Modulation and Coding) level by link in consideration of the acquired channel statuses(904); determining a specific relay mode having the maximum processing rate out of plural relay modes(906); and transmitting signals in correspondence to the determined AMC level and specific relay mode(910).