Aging adversely affects the elastic and ultimate properties of human cortical bone as seen in uniaxial tests in quasi static loading, high strain rate impact or fatigue. Little is known about the full effects of aging on toughness and its relationship with strength. In the present article the elastic modulus (E), strength (σ_f), fracture toughness (K_C and J-integral), and work of fracture (W_f) were determined in specimens of male human femoral bone aged between 35–92 years. In this way we investigated whether fracture of bone in three situations, allowing various amounts of damage prior to fracture, can provide a better insight into the fracture process and also the relative importance of these experimental methods for assessing the soundness of bone material. We found a steady and significant decrease with age for all these mechanical measures. E fell by 2.3%, from its value of 15.2 GPa at 35 years of age, per decade of later life;​ σ_f fell similarly from 170 MPa by 3.7%;​ K_C from 6.4 MPa m^1/2 by 4.1%;​ J-integral from 1.2 kJ m⁻² by 3%, and the W_f from 3.4 kJ m⁻² by 8.7%. In aging bone there was a deterioration in the elastic properties of the material. This reduced the (elastically calculated) critical stress intensity level (K_C) required to initiate a macrocrack, or the nonlinear energy associated with the onset of fracture (J). The macrocrack was preceded by less damage, and once created needed less energy to drive through the tissue (W_f).