The response of compact bone tissue to a fluctuating compressive fatigue load was examined and the S-N curve relating the maximum applied compressive stress and the number of cycles to failure was established. Cylindrical specimens extracted longitudinally from the mid-diaphysis of fresh bovine femora were fatigued at maximum compressive stress levels between −11500 and −15000 psi. The corresponding median fatigue lives ranged from 4.42 × 10⁶ cycles (−11500 psi) to 1.04 × 105 cycles (−15000 psi), and fatigue lives greater than 10⁷ cycles were observed at the lowest stress level. The tissue density and the elastic modulus and failure stress in compression of the compact bone source material were also measured.