Photo-density and fracture load of the femoral neck were both measured, for an experimental osteoporosis, induced by hemicordotomy combined with ovariectomy in the rat. A significant decrease in these values directly proportionate to the progression of the osteoporosis, was observed. Photodensity of the femoral neck showed a significant correlation to the fracture load and also to the cortical thickness index (CTI) and bone density (ΣGS/D) at the femoral midpoint. Furthermore, administration of 1α(OH) vitamin D3 caused a significant increase in the photo-density and fracture load of the femoral neck.