The present study investigates the thermal radiation effect on unsteady magneto hydro dynamic (MHD), mixed convection flow of a micro polar fluid past an infinite, steadily moving plate with variable suction. The dimensionless equations which govern the flow, such as conservation of mass, linear momentum, angular momentum, and energy, are solved by using a regular perturbation method. The expressions for velocity, micro rotation, and temperature are obtained. With the aid of these, the expressions for Skin-friction and Nusselt number are obtained and the behavior of various physical parameters on the above flow quantities is discussed with the help of the graphs. The existence of the magnetic field and as well as radiation decrease the velocity throughout the boundary layer. The effect of increase in the plate moving velocity and the radiation parameter, manifest in a linearly decreasing surface skin-friction on the porous plate, whereas the surface heat transfer from the porous plate tends to increase, with an increase in Prandtl number.