The microscopic yield stress (the stress to produce a plastic strain of 2×10−6 in./in.) and the variation of plastic strain with applied stress have been established for bone. A feature of the deformation is the large anelastic contraction which occurs after unloading plastically strained specimens. The fracture characteristics of bone, as determined in impact loading and tensile experiments, are a function of specimen orientation and are also notch sensitive. A study of the temperature dependence of fracture in the range from −190° to 900°C shows that specimens oriented parallel to the length of the bone exhibit a pronounced maximum in strength at 0°C.