We investigated the micromechanical properties using doses from 1 up to 7 Gray and could observe a roughening on the surface of the bone material in the microscopic range by scanning acoustic microscopic measurements. In addition, a preceding irradiation promoted an extension of microcracks during the polishing process indicating an embrittlement. After irradiation and removal of the surface layer the SAM measurements indicate a preferential increasing of hardness of softer regions. These results are consistent with our measurements by environmental scanning electron microscopy.