A method is provided for providing a multicast service by a base station (BS) in a wireless communication system. The method includes transmitting an Nth data traffic corresponding to a multicast service to a plurality of mobile stations (MSs) through a multicast channel in an Fth frame; determining whether a Negative Acknowledgement (NACK) message indicating a failure to receive the Nth data traffic is received from at least one MS in an (F+1)th frame; and when the NACK message is received, retransmitting the Nth data traffic to an MS, which transmitted the NACK message, through an other channel different from the multicast channel in an (F+2)th frame.