A method for efficiently transmitting downlink control information is described. A method for transmitting control information in a multiple antenna system which can simultaneously transmit a maximum of two codewords includes transmitting modulation and coding scheme (MCS) information, a new data indicator (NDI) and a redundancy version (RV) for information blocks transmitted through the two codewords, and transmitting additional control information including at least one of a swapping indicator and enable/disable information. The swapping indicator indicates whether or not swapping occurs between the information blocks transmitted through the two codewords, and the enable/disable information indicates whether or not any one of transmissions through the two codewords is disabled. The swapping indicator is reserved when any one of transmissions through the two codewords is disabled, thereby reducing signaling overhead and efficiently transmitting necessary information.