The present invention relates to a method for performing retransmissions by a transmission end in a wireless communication system. In particular, the method includes the steps of: re-transmitting a data unit to a reception end; and increasing a retransmission counter associated with the data unit, when the retransmission counter associated with the data unit reaches to a max value, reporting a max retransmission indication to an upper layer and setting the retransmission counter associated with the data unit to zero.