Using Norland-Cameron photon-absorption technique, bone mineral content of 436 healthy aged was measured and compared with that of 198 healthy, aged 21-50. Bone mineral content of postmenopausal females decreased continuously with age and bone mineral content of males began to decrease at age over 70. Bone width and menopausal age seemed to be important factors influencing bone mineral content, but previous physical activity seemed to have no effect on the bone mineral content of the aged.