A method and apparatus for transmitting a time stamp to provide a multicast service by a base station in a communication system is provided. Upon receipt of a multicast service request from a first terminal, the base station determines whether a second terminal exists that was receiving data of the multicast service before the multicast service request is received. The base station determines whether the multicast service data is being transmitted to the second terminal in a unicast manner when the second terminal exists. The base station allocates a first multicast Connection Identifier (CID) and a first time stamp of an earliest order to the second terminal when the multicast service data is being transmitted to the second terminal in a unicast manner. After allocating the first time stamp to the second terminal, the base station allocates the first multicast CID and a second time stamp having a next earliest order to the first terminal. The base station transmits the first time stamp and the second time stamp using a resource allocation message. The first time stamp and the second time stamp represent different playback times of the multicast service data.