Modeling the effects of RF penetration in magnetic resonance (MR) imaging requires a knowledge of the local values of conductivity and permittivity. The inverse problem of determining the electlic properties of the materid under investigation using the M R images themselves has not previously been addressed.W e review such an approach for the heterogeneous layer model and examine the parsmeter sensitivity l o geometry and signal-to-noise ratio. For a few-layer system, it is within the realm of present day M a systems to extract the electric properties 10 within 10% or better. Knowledge of the electrical propertis will then allow a better prediction of the R F penetration and power deposition at high fields.