Mixed convective flow and heat transfer are considered in the annular region between concentric cylinders filled with fluid-saturated porous material. The inner cylinder is heated and the outer cylinder cooled. The heat transfer rate from the inner cylinder as a function of the superimposed flow is studied, allowing for possible buoyancy effects. Both horizontal and vertical annuli are included in the study. The equations governing flow are numerically solved. Results have been obtained for a range of Peclet numbers, 0 < Pe < 10 and Rayleigh numbers, 0 < Ra < 500. The mixed convection regime is expected to be predominant for this range of parameters.