A method of transmitting and receiving buffer status information and CSI for scheduling of an uplink packet data service in a mobile communication system supporting the uplink packet data service. The buffer status information represents the status of a UE buffer having packet data and the CSI represents the uplink transmit power of a UE. The UE initially transmits the buffer status information and the CSI, if the amount of packet data in the buffer is at least equal to a predetermined threshold. Upon generation of new packet data in the buffer, or according to a predetermined buffer status interval, the UE transmits the buffer status information.