A method and apparatus for transmitting/receiving an ACKnowledgement/Negative ACKnowledgement (ACK/NACK) signal to support packet data retransmission in an Frequency Division Multiple Access (FDMA) wireless communication system are provided, in which a User Element (UE) generates an ACK/NACK signal for received packet data, determines whether the UE is set to support ACK/NACK repetition, transmits the ACK/NACK signal on a basic response channel mapped to one of a DCH on which the packet data was received and a Shared Control Channel (SCCH) carrying scheduling information about the packet data, if the UE is not set to support ACK/NACK repetition, and selects one of supplementary response channels for each ACK/NACK repetition, the supplementary response channels being allocated for ACK/NACK repetition and repeatedly transmits the ACK/NACK signal on the selected supplementary response channel according to a predetermined repetition factor, if the UE is set to support ACK/NACK repetition.