A method of encoding data using a parity check matrix, a method of decoding encoded data, and a data retransmission method using the same are disclosed. A data retransmission method in a communication system includes transmitting a codeword encoded by a first parity check matrix corresponding to a first coding rate, among at least two parity check matrixes corresponding to different coding rates, receiving NACK from the receiver in response to the codeword, and transmitting parity bits encoded by some of the second parity check matrix corresponding to a second coding rate, among the at least two parity check matrixes, to the receiver.