A method to estimate the resistivity of composite structures using an inverse problem solving algorithm is presented that uses voltage distribution on the structure as data. Electrodes attached to the surface of the structure are used to obtain voltage data in response to current injection through a pair of these electrodes. The forward problem involves using the finite element method to predict the voltages at the electrodes using known values of resistivity. The inverse problem involves solving for the resistivity values using the experimentally measured voltage data. If the material does not have uniform properties, the computed resistivity values are average values. Damage or defect in a composite structure can significantly alter the average resistivity of the structure. To explore the possibility of using this approach to detect defects in manufacturing or damage due to loading, the effect of artificially induced damage/defect on the overall resistivity of the structure is studied.