In this paper, the effects of internal heat generation or absorption on free convection flow of a nanofluid past an isothermal inclined plate have been investigated numerically. The governing boundary-layer equations are first transformed into a system of coupled nonlinear ordinary differential equations using similarity variables. An efficient implicit finite-difference scheme known as the Keller-box method is employed to solve the resulting nonlinear equations. The effects of internal heat generation or absorption parameter on the flow fields have been presented graphically and discussed. It is found that the rate of heat transfer decreases with increasing heat generation, Brownian motion and thermophoresis parameters whereas it increases with increasing heat absorption parameter and Prandtl number. © (2014) Trans Tech Publications, Switzerland.