The mechanical properties of cortical bone have been extensively studied at the macrostructural scale. However, knowledge of the macroscopic mechanical properties is not sufficient to predict local phenomena, such as damage or bone remodelling, both of which are dependent on local mechanical behaviour. The objective of this study was to quantify the mechanical properties of human cortical bone inside the microstructure using micro-extensometry technique. At the scale of an osteon, the present study demonstrated that the strain was heterogeneous and its value depended strongly on the applied loading direction.