A communication system using multi-phase clock signals. The communication system includes a transmitter and a receiver. The transmitter outputs first data and a clock signal based on first multi-phase clock signals, and performs a coarse lock operation on the clock signal in response to a bit lock detection signal indicating whether or not the first data are bit-locked. The receiver receives the first data and the clock signal from the transmitter, generates second multi-phase clock signals based on the clock signal, generates second data by sampling the first data based on the second multi-phase clock signals, and performs a fine lock operation on the second multi-phase clock signals in response to the bit lock detection signal. Therefore, a jitter noise may be reduced and a size of a multi-phase clock generator included in the receiver may be reduced.