There is provided a reverse data rate determining method in a mobile communication system for high data rate transmission such as an HDR system. An AN within a cell calculates the total load of a reverse link by measuring the total energy of the reverse link from ATs within the cell. The AN calculates the share of each AT in the total reverse link load. If the load share of an AT is greater than a threshold predetermined individually for the AT, the AN determines that the AT should reduce its data rate.