Channel state information at the transmitter (CSIT) can be exploited to improve performance in MIMO wireless systems through a precoding operation at the transmitter. Precoding techniques use CSIT to encode the information symbols into transmit vectors. Typically, an information symbol vector u is encoded into a transmit vector x using the transformation x = Tu, where T is referred to as the precoding matrix. The precoding matrix T is chosen based on the available CSIT. Precoding on point-to-point MIMO links and multiuser MIMO links is common. In addition, multiuser MIMO precoding in multicell scenarios is of interest. In this chapter, precoding schemes for large MIMO systems are considered.