Electron probe microanalysis (EPMA) is a useful method for element mapping analysis. However, the samples to be subjected are restricted to heat-stable materials, such as metals and ceramics, because irradiation of focused electron beam generates intense heat. In order to apply EPMA to tissues, we sliced the samples off to sections of appropriate thicknesses by use of polished carbon block as a support, such sections were very stable against the intense electron beam. Thus the mapping analysis by EPMA has been applied to tissue sections for histopathologic diagnosis. The principal advantage of this method is high detection sensitivity that is about 1×10⁶ at./µm² in case of copper. This was confirmed by analyzing thin standard films containing the element. In addition, exact linear relationship between the amount of copper atoms and the characteristic X-ray intensity was established in the range up to 15×10⁶ at./µm². The usefulness of this method for histopathologic diagnosis, such as Wilson's disease, was confirmed by mapping analysis of many section samples.