The present invention relates to a method and apparatus for transmitting and receiving data. A data transmission method from a sender terminal to a receiver terminal in a MIMO system using a variable frequency band according to one embodiment of the present invention comprises: repeatedly generating a signal field depending on a frequency band that is applied to the transmission of a data frame; generating a data field including the data; generating a data frame including the signal field and the data field; and transmitting the data frame to the receiver terminal. The present invention is advantageous in that a signal field which is transmitted together with the data being transmitted from the sender terminal to the receiver terminal in the MIMO system can be sent more efficiently.