Bone fragility can be defined as an increased risk of fractures. Advanced age and bone diseases such as osteoporosis increase the fracture risk. Understanding the effects of osteoporosis and its treatments requires a description of the mechanical behavior of bone tissue. To this end, an entire bone can be studied, or the cortical and trabecular components can be investigated separately. We review the biomechanical tests available for measuring the ability of bone to withstand torsional, compressive, tensile, and bending forces.