The present work experimentally investigates the effect of synthetic jets on the heat transfer performance in a microchannel heat sink. The heat sink consists of five parallel rectangular microchannels measuring 500 μm wide, 500 μm deep, and 26 mm long each. An array of synthetic jets with 100 μm diameter orifices is placed right above the microchannel with a total of eight jet orifices per channel. Microjets are synthesized from the fluid flowing through the microchannel. Periodic disturbances are generated when the synthetic jets interact with the microchannel flow. Heat transfer performance is enhanced as local turbulence is generated and penetrates the thermal boundary layer near heated channel wall. The effects of synthetic jets on microchannels heat transfer performance are studied for several parameters including the channel stream flow rate, the synthetic jets strength and operating frequency. It shows that the synthetic jets have higher heat transfer enhancement for microchannel flow at lower channel flow rates. A maximum of 130% heat transfer enhancement is achieved for some test cases. The pressure dynamics introduced by the synthetic jets are also investigated. The synthetic jets cause a minor increase in the pressure drop.