Concrete resistivity is increasingly being used for diverse applications like the detection of fibers, the evaluation of the degree of water saturation and then of the risk of rebar corrosion, the prediction of the service life or as indicator of the porosity of the concrete. There are several methods to measure the electrical resistivity of the concrete which basically are based in a direct measurement using regular geometries of the specimen and of the electrodes or the measurement by the

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... c" or the four point (Wenner) method. It is said that the measurement has in any case to be made in absence of a rebar in the specimen or below the measurement place due to the presence of a metallic piece modifies the measurement. In present work is described the study made to calculate the resistivity by the Four-Point method in specimens containing a centered bar. The theoretical calculations were carried out by a finite element method and the results were verified in several specimens having the same resistivity than the numerical examples. Shape factors and a mathematical expression are given for different variables tested.