The mechanical properties of machined cortical bone specimens from human femora and tibiae were determined in tension, torsion, and compression for a population ranging in age from twenty-one to eighty-six years. No significant differences were found between the mechanical properties of male and female specimens. Tibial specimens had greater ultimate strength, stiffness, and ultimate strain than femoral specimens. Consistent decreases with age for all mechanical properties except plastic modulus were found in the femoral but not in the tibial specimens. No consistent significant differences in tension properties were found in specimens from normal, osteoporotic, and corticosteroid-treated individuals.