A study of the compressive failure strength and mineral content of cancellous bone was performed. The matrial was obtained from 150 selected autopsies. Exclusion of thirteen of the selected cadavera on clinical or histological grounds left 137 cadavera for review: seventy-two male and sixty-five female. Cubes of cancellousbone from the third lumbar vertebral body and from the calcaneal tuberosity were obtained in a standard way and subjected to compressive loading and ash-weight determination. The findings justified the following conclusions:

1. Compressive failure strength is a reliable function of the mineral content of cancellous bone in the vertebra or the calcaneus. This relationship is maintained irrespective of age or sex.

2. In an autopsy population in which every effort was made to select normal individuals there is a definite and progressive trend toward decreasing bone strength and mineral content with advancing age.

3. There is ho significant difference between the strength or mineral content of cancellous bone of male and female cadavera below the age of fifty. Over the age of fifty the strength and mineral content is significantly lower in female cadavera.

4. The decrease in bone mineral and strength appears to develop earlier in the vertebra than in the calcaneus.

5. It is suspected that changes which parallel those observed in female cadavera would be seen in male cadavera as well if the population sampled included a larger number of individuals over the age of eighty.

6. The relationship between calcaneal mineral content and compressive stregth and the same determinations in the vertebra is only fair. The fact that the correlation is particularly low in males and in the younger group suggests that activity may influence cancellous bone strengh and mineral content. Evidence is offered to show that this influence is exerted by way of the distribution and orientation of trabeculae.

7. The effect of generalized osteoporosis on the calcaneus is delayed and appears to be influenced by activity. It would seem that the calcaneus is an unsatisfactory bone for following the dynamics of a generalized demineralizing process.