The present invention relates to a wireless communication system, and more particularly, to a method and an apparatus for transmitting reference signals in uplink MIMO transmission. According to one embodiment of the present invention, the method for transmitting uplink signals through a terminal in the wireless communication system comprises the steps of: receiving control information including the information on a cyclic shift and/or an orthogonal cover code; allocating the multiplexed reference signals onto an uplink subframe; and transmitting the subframe through a multi-antenna. When the uplink MIMO transmission is multiuser MIMO transmission, the reference signals of the terminal and the reference signals of other terminals can be multiplexed by using the orthogonal cover code.