Two groups of subjects, ranging from 20 to 40 years of age the first and from 65 to 85 years the second, have been submitted to bone density measurements by EMI CT 5005 All-Purpose Scanner (140 kV; 28 mAs) and the average values compared. The difference between the average values of the two groups has been taken as a scale of points to evaluate the mineral contents of bone. By the group of older subjects the loss in trabecular bone (lumbar spine L2/L3) proved to be 59.51 EMI units, corresponding to the 47.6% of the mineral contents (p = < 0.01); the loss in compact bone (femur) was 6.6 EMI units corresponding to 5.28% of the mineral contents (p = < 5). The trabecular bone and compact bone average values added together give a whole-skeleton mineral contents index. This index applied to the group of older subjects showed a diminution of 65.81 EMI units indicating a 52.6% loss of mineral contents. Repeated measurements taken at a distance of time proved the method to be fairly reliable with acceptable degree of accuracy (+/- 5%). A tentative approach to clinical use of the skeletal index gave satisfying results.