A method for performing data communication in a mobile communication system is disclosed. The method serves to increase channel efficiency by connecting and releasing channels in accordance with the presence/absence of control and traffic data transmitted during packet data communications. Transmission power and mobile terminal battery power are conserved by controlling outputs of a dedicated control channel and a pilot channel when data transmission is discontinued temporarily during data communications. The mobile communication system includes an active state in which user data is transmitted through a dedicated traffic channel and control messages are transmitted through a dedicated control channel. In accordance with the method, a transition is made from the active state to a first control hold state when there is no control or user data to transmit for a first preset time. In the first control hold state, the dedicated traffic channel is released while the dedicated control channel and a reverse pilot channel are maintained. A transition is made from the first control state to a second control hold state when there is no user or control data to transmit for a second preset time. In the second control hold state, which is a resource save sub-state, the transmission outputs of the dedicated control channel and reverse pilot channel are interrupted to conserve power.