The present invention relates to a wireless communication system, and more particularly, to a method and apparatus for transmitting a downlink reference signal in a wireless communication system that supports multiple antennas. A method for transmitting channel state information-reference signals (CSI-RS) for two or more antenna ports according to one embodiment of the present invention comprises the steps of: mapping the CSI-RSs for the two or more antenna ports in predetermined patterns on a data region of a downlink subframe: an transmitting the downlink subframe mapped with the CSI-RSs for the two or more antenna ports, wherein the predetermined patterns are defined as patterns differing by a cell, and the different patterns may be defined as the predetermined patterns being shifted in a temporal range, frequency range, or a temporal range and a frequency range.