A numerical investigation is performed into the natural convection heat transfer performance and entropy generation of Al2O3-water nanofluid in an inclined wavy-wall cavity. The simulations focus specifically on the effects of the cavity inclination angle, nanoparticle volume fraction, Rayleigh number and wave amplitude of the wavy surface on the flow streamlines, isotherm distribution, Nusselt number and entropy generation within the cavity. The range of the studied parameters is as follows: cavity inclination angle from 0 degrees to 360 degrees, nanoparticle volume fraction from 0% to 4%, Rayleigh number from 10(2) to 10(6), wavy-surface amplitude from 0.0 to 0.5. The results show that the inclination angle has a strong effect on the flow streamlines, isotherms, local entropy generation and heat transfer performance; particularly at higher Rayleigh numbers. In addition, it is shown that for a given Rayleigh number and cavity inclination angle, the mean Nusselt number increases and the total entropy generation decreases as the volume fraction of Al2O3 nanoparticles increases. Finally, it is shown that for a constant Rayleigh number and inclination angle, the Nusselt number in a wavy-surface cavity is higher than that in a regular cavity, while the total energy generation is lower. (C) 2016 Elsevier Ltd. All rights reserved.