This study examines the influence of multiple injection/suction at bottom/top walls on non-Darcy mixed convection flow in a vertical square enclosure filled with fluid saturated porous medium. The coupled non-linear partial differential equations modeling the fully developed Forchheimer extended Darcy flow are solved by finite element method. Detailed numerical simulations are carried out for a wide range of parameters such as Grashof number (Gr* is an element of [0,10]), Rayleigh Number (Ra is an element of [50,500]), injection/suction velocity (a is an element of [0,0.5]), injection/suction window width (D/H is an element of [0,0.3]). The computed flow and temperature fields are analysed through streamlines, isotherms and cumulative heat flux plots. While the Nusselt number increases with increasing (D/H) it is found to decrease with increasing 'a'. Inertial forces significantly favor the heat transfer process when thermal buoyancy forces are large (i.e. for Ra > 100). (C) 2010 Elsevier Ltd. All rights reserved.