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Micro-finite element ([Mu]FE) models based on high-resolution images have enabled the calculation of elastic properties of trabecular bone in vitro. Recently, techniques have been developed to image trabecular bone structure in vivo, albeit at a lesser resolution. The present work studies the usefulness of such in-vivo images for [Mu]FE analyses, by comparing their [Mu]FE results to those of models based on high-resolution micro-CT ([Mu]CT) images. Fifteen specimens obtained from human femoral heads were imaged first with a 3D-pQCT scanner at 165 [micro]m resolution and a second time with a [Mu]CT scanner at 56 [micro]m resolution. A third set of images with a resolution of 165 [micro]m was created by downscaling the [Mu]CT measurements. The [Mu]FE models were created directly from these images. Orthotropic elastic properties and the average tissue von Mises stress of the specimens were calculated from six FE-analyses per specimen. The results of the 165/[micro]m models were compared to those of the 56 [micro]m model, which was taken as the reference model. The results calculated from the pQCT-based models, correlated excellent with those calculated from the reference model for both moduli ([R.sup.2] [is greater than] 0.95) and for the average tissue von Mises stress ([R.sup.2] [is greater than] 0.83). Results calculated from the downscaled micro-CT models correlated even better with those of the reference models ([R.sup.2] [is greater than] 0.99 for the moduli and [R.sup.2] [is greater than] 0.96 for the average yon Mises stress). In the case of the 3D-pQCT based models, however, the slopes of the regression lines were less than one and had to be corrected. The prediction of the Poisson's ratios was less accurate ([R.sup.2] [is greater than] 0.45 and [R.sup.2] [is greater than] 0.67) for the models based on 3D-pQCT and downscaled [Mu]CT images respectively). The fact that the results from the downscaled and original [Mu]CT images were nearly identical indicates that the need for a correction in the case of the 3D-pQCT measurements was not due to the voxel size of the images but due to a higher noise level and a lower contrast in these images, in combination with the application of a filtering procedure at 165 micron images. In summary: the results of [Mu]FE models based on in-vivo images of the 3D-pQCT can closely resemble those obtained from [Mu]FE models based on higher resolution [Mu]CT system. [DOI: 10.1115/1.1352734]