The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for transceiving an uplink hybrid automatic repeat request (HARQ). According to one embodiment of the present invention, a method for performing a HARQ operation in a terminal of a wireless communication system comprises the steps of: receiving, in a subframe n, an uplink grant message for first uplink data from a base station; determining a first HARQ process from among a plurality of HARQ processes associated with the subframe n; and transmitting, in a subframe n+k, the first uplink data to the base station through the first HARQ process.