Secondary flow is employed in micro channel heat sink (MCHS) by introducing slanted passage in the channel wall between the adjacent channels in alternating orientation. The intervallic passage causes disruption in the hydrodynamic boundary layer and redevelopment at the leading edge of the following wall. This phenomenon decreases the average thermal boundary layer thickness, thus enhances the heat transfer performance with minor pressure drop due to combined effect of thermal boundary layer re-development and flow mixing. The data presented in comparison of simple MCHS. The results showed that the overall performance of MCHS with alternating slanted passage (MASP) increased by 146% and thermal resistance reduced to 76.8% when compared with simple MCHS. It has to be highlighted that contradicting from the usual phenomenon where improvement in heat transfer accompanied with increment in pressure loss, thermal enhancement in present study comes together with reduction in pressure drop up to 6% compared to the simple one. (C) 2014 Elsevier Ltd. All rights reserved.