The fracture toughness of the right femoral neck, femoral shaft, and tibial shaft of matched cadaveric bones, ages 50 to 90 years, was compared. Results of this study indicate that tensile (G_Ic) and shear (G_IIc) fracture toughness vary depending on bone location. The femoral neck has the greatest resistance to crack initiation for both tension and shear loading while the femoral shaft has the least. The relationship between age and the fracture toughness of the femoral neck and shaft was investigated. G_c of the femoral shaft significantly decreased with age for mode I and was nearly significant for mode II. Fracture toughness of the femoral neck did not change with age for the later decades of life. Implications of these findings are discussed.