A numerical investigation of unsteady magnetohydrodynamic free convection in an inclined square cavity filled with a fluid-saturated porous medium and with internal heat generation has been performed. A uniform magnetic field inclined with the same angle of the inclination of the cavity is applied. The governing equations are formulated and solved by a direct explicit finite-difference method subject to appropriate initial and boundary conditions. A parametric study illustrating the influence of the Hartmann number, Rayliegh number and the inclination angle of the cavity on the flow and heat transfer characteristics such as the streamlines, isotherms and the Nusselt number is performed. The velocity components at mid section of the cavity as well as the temperature profiles are reported graphically. The values of Nusselt number for various parametric conditions are presented in tabular form.