Numerical results have been obtained for the effects of wall conduction and radiation heat exchange between surfaces on laminar natural-convection heat transfer in a two-dimensional rectangular cavity. Parametric heat transfer calculations have been performed and results are presented In graphic and tabular form. Local and average Nusselt numbers along the cavity walls are reported for a range of parameters of physical interest. The findings suggest that the local or the average Nusselt number may not be a meaningful parameter for use in conjugate heat transfer problems. The results indicate that natural-convection heat transfer in the cavity is reduced by heat conduction in the walls and radiation exchange among surfaces.