The distribution and anisotropy of the stiffness of cancellous bone in the human patella was studied by compression testing of small cubes cut from autopsy speciments. The observed variations bear a definite relationship to the internal architecture which can be accounted for by a simple sheet-and-strut model. The observed stiffness can be calculated with reasonable accuracy for loads approximately parallel to the sheets, with the proposed model. The spatial distribution of the stiffness was plotted and a close relationship to mechanical function is suggested.