- This paper is focused on specification of conditions at failure in bovine cortical bone. Both experimental and analytical studies are conducted. The experimental part includes a series of novel direct shear tests which examine the sensitivity of shear strength to the applied normal stress for different orientations of the sample microstructure. These experiments are supplemented by standard axial compression and tension tests in order to define and quantify a general form of failure criterion. The analytical part examines two different methodologies, viz. critical plane approach and microstructure tensor approach, for defining the anisotropic strength criterion. A procedure for identification of material parameters is outlined which is based on the results of the performed material tests.