A method and apparatus for power control of the re-transmission data packet in a wireless communication system is disclosed. A first wireless communication device is provided that receives (210) a data packet from a second wireless communication device and determines (220) if the data packet is correctly decoded. If the data packet is not correctly decoded, the first wireless communication device calculates (230) a first re-transmission power required for correctly decoding the data packet based on a signal to noise ratio (Eb/No) versus frame error rate (FER) relationship. And further calculates a power difference (240) between the calculated re-transmission power and the power of the received data packet and transmits the power difference (250) to the second wireless communication device. The second wireless communication device calculates (340) a second re-transmission power based on the received power difference and re-transmits (350) the data packet at the calculated re-transmission power.