In this paper a comprehensive review of heat transfer enhancement through microchannels has been presented. Over the past few years due to multifunction, shrinking package size and high power dissipation, the heat flux per unit area has increased significantly. Microchannels, with their large heat transfer surface to volume ratio and their small volumes, have shown a good thermal performance. Microchannels have been proven to be a high performance cooling technique which is able to dissipate heat flux effectively from localized hot spots over small surface area. A good amount of heat transfer augmentation techniques have been reported on flow disruption through microchannel. These techniques promote free stream separation at the leading edge which results in boundary layer development and enhanced mixing leading to increased heat transfer. Flow disruption can be achieved through passive surface modifications, such as, shape of channel, dimple surfaces, ribs, cavities, groove structures, porous medium, etc. Combined effects of these geometrical configurations in heat transfer augmentation are also reported in the literature. In this paper recent developments in experimental and numerical simulations of single-phase liquid cooled microchannel have been discussed to analyze the pressure drop, friction and heat transfer characteristics due to different flow conditions, roughness structure and passive surface modifications. It has been observed that the flow disruption techniques are effective for heat transfer enhancement with lower penalties of increased pressure drop. The review concludes with suggestions for future research in this area. In the paper a comprehensive review of heat transfer enhancement through microchannels has been presented. Over the past few years due to multifunction, shrinking package size and high power dissipation, the heat flux per unit area has increased significantly. Microchannels, with their large heat transfer surface to volume ratio and their small volumes, have shown a good thermal performance. Microchannels have been proven to be a high performance cooling technique which is able to dissipate heat flux effectively from localized hot spots over small surface area. A good amount of heat transfer augmentation techniques have been reported on flow disruption through microchannel. These techniques promote free stream separation at the leading edge which results in boundary layer development and enhanced mixing leading to increased heat transfer. Flow disruption can be achieved through passive surface modifications, such as, shape of channels, dimple surfaces, ribs, cavities, groove structures , porous medium, etc. Combined effects of these geometrical configurations in heat transfer augmentation are also reported in the literature. In this paper recent developments in experimental and numerical simulations of single-phase liquid cooled microchannel have been included to analyze the pressure drop, friction and heat transfer characteristics due to different flow conditions, roughness structure and passive surface modifications. It has been observed that the flow disruption techniques are effective for heat transfer enhancement with lower penalties of increased pressure drop. area.