Mechanical properties of bone tissue have been studied to determine the viscoelastic behavioral characteristics. Whole bones, however, have not been examined to determine the effect of loading rate on ultimate properties. This paper presents results obtained from torsional tests of fresh dog tibiae and femora tested at both high and low loading rates. The data which is presented includes energy absorption required for failure, maximum torque, and maximum angular deformation before failure. A comparison of these properties is made between paired specimens tested at high rates of loading and at low rates of loading. The findings indicate increased energy absorption, increased maximum torque, and slightly increased angular deformation under rapid loads. In addition there is a strong suggestion of a different fracture pattern.