Power dissipation is one of the most important design objectives in integrated circuit, after speed. Digital signal processing (DSP) circuits whose main building block is a Multiply Accumulate (MAC) unit. High speed and low power MAC unit is desirable for any DSP processor. This is because speed and throughput rate are always the concerns of DSP system. This paper explores the design of low power MAC unit with block enable technique to reduce power dissipation. The whole MAC unit is implemented using 90-nm CMOS process technology. The whole MAC unit is operated at 314.268MHz with 1.5V supply voltage. The result analysis shows that the power consumption is reduced by using block enable technique.