In this paper, initial clinical data from an intraoperative MR system are compared to calculations made by a three-dimensional finite element model of brain deformation. The preoperative and intraoperative MR data was collected on a patient undergoing a resection of an astrocytoma, grade 3 with non-enhancing and enhancing regions. The image volumes were co-registered and cortical displacements as well as subsurface structure movements were measured retrospectively. These data were then compared to model predictions undergoing intraoperative conditions of gravity and simulated tumor decompression. Computed results demonstrate that gravity and decompression effects account for approximately 40% and 30%, respectively, totaling a 70% recovery of shifting structures with the model. The results also suggest that a non-uniform decompressive stress distribution may be present during tumor resection. Based on this preliminary experience, model predictions constrained by intraoperative surface data appear to be a promising avenue for correcting brain shift during surgery. However, additional clinical cases where volumetric intraoperative MR data is available are needed to improve the understanding of tissue mechanics during resection.