The purpose of this study is to present a multiscale approach for the biomechanical characterization of the human liver and spleen. A four step approach was taken to quantify the injury mechanism, biomechanical response, and rate dependent constitutive material models for each organ. First, the CIREN and NASS-CDS databases were examined to determine the crash characteristics which result in liver and spleen injuries. From this data, the injury mechanism relative to loading directions and loading rates could be approximated. Second, whole fresh human organs were tested with in 48 hours of death using indenter-style compression tests. Sub-failure tests, up to 20% compression, were performed at multiple loading rates, followed by a failure test. Third, fresh human organs were processed into either dog-bone tension coupons or cylindrical compression coupons and tested within 48 hours of death at multiple strain rates to the point of failure. Fourth, an optimization routine and FEM of the coupons tests was developed to determine the best constitutive model for each organ. The data from this study shows that the response of human liver and spleen is both non-linear and rate dependant. It is anticipated that the data from this research will enhance the understanding of internal organ injuries and provide a foundation for future human internal organs finite element models.