A method and apparatus for transmitting acknowledgements in response to data packets in wireless communication are disclosed. A recipient may receive a plurality of data packets from a plurality of stations and transmit acknowledgements for the data packets to the originating stations in a single transmission. The acknowledgements may be transmitted using multi-user multiple-input multiple-output (MU-MIMO). Alternatively, the acknowledgements may be aggregated and transmitted in the single transmission. A short acknowledgement (ACK) frame may be sent in response to a received frame. The short ACK frame may include an ACK sequence corresponding to a sequence identity (ID) included in the received frame. The short ACK frame may include a short training field (STF) and the ACK sequence. The short ACK frame may be transmitted with a short ACK indication. The short ACK frame may be sent in response to an indication included in the received frame.