The aim of this paper is to investigate numerically the heat and fluid flows in laminar slip-flow in parallel plates microchannel with uniform temperature on the outer surface of the plates. The effects of fluid to wall conduction, entrance effects and viscous dissipation in gaseous flow will be considered. The fluid is assumed to be incompressible and with constant properties. A finite volume computational in-house program is used to solve the two-dimensional Navier− Stokes and energy equations with slip velocity and temperature jump at the fluid/solid interface. The results are obtained for different Brinkman numbers, Knudsen numbers, and thicknesses of the plate. The combined effects of viscous dissipation and wall conduction on the heat transfer rate are demonstrated.