The generation of per stream Channel Quality Information (CQI) in a Multiple-Input Multiple-Output (MIMO) wireless communication system is provided. An apparatus includes a receiver for receiving signals from a transmitting end via a plurality of antennas; an estimator for estimating channels per antenna in relation with the transmitting end using the received signals and constituting a channel matrix; and a generator for deriving per stream effective noise when a lattice reduction scheme is adopted and generating per stream CQI using the per stream effective noise. Thus, feedback information for a Closed Loop (CL) MIMO system can be produced by generating the per stream CQI using the effective noise obtained through the lattice reduction.