Quantitative histologic evaluation of hone biopsies has improved the understand ing of different systemic hone diseases. Therefore they are being used by several laboratories in connection with various structural and pathophysiological problems (BOKDIEK. MATHAJT. MIRAVET and llioco [1964], FROST [1963]. Jowsey, KELLY, Rices, BIANCO, SCIIOLZ and GERSIION-COHEN [1965], MI LLER and SCHENK [1966], VANDER SLUYS, SMEENK and VAN DER IIEUL [1963], WAGNER [1965]). Different microscopic methods have been developed in order to determine the amount of hone formation and hone resorption. The results of these remodelling processes are reflected in structure, that is form, mass and arrangement of the inter cellular substance in each hone of the skeleton. Under physiological conditions, me chanical stability is maintained by a minimum amount of hone material. This sug gests the presence of a very accurate control system, regulating the relation of hone structure and function (PAUWELS [1954], Houx [1B951). Insight into this relationship has stimulated comparisons with engineering prin ciples. MEYER and CULMANN [18671compared the structure of cancellous bone in the proximal end of the femur to the construction of a crane. They pointed out that the carrying capacity of such a structure depends less on the amount of material used than on the adequate spatial arrangement and form of each element (PAUWELS 11954. 1965]). Quantitative statements concerning structure and stability of bone, therefore, should he based not only upon the volume and density of intercellular substance alone, but also upon the arrangement and dimensions of the trabeculae. Chemical analysis of bone tissue (ARNOLD. BARTLEY, TONT and Jenkins [1966], BELL, DUNBAR and BECK [1967]) as well as x-ray densitometry of hone (HEVCK [1965], Jowsey [1965] OESER and KROKOWSKI [1966]) are not suitable methods, because they arc conclusive only as to the volume and the mineralization of the inter cellular substance. Previous quantitative histological measurements have all been limited to the determination of volumetric density, that is the ratio of intercellular substance to the total volume of the bone tissue in question (ATKINSON [1967], BARER and Jowsey [1967]. DUNNILL, ANDERSON and WHITEHEAD [1967], FROST [1963], NORDIN [1964], WAGNER [1965]). Furthermore, there have been few attempts made to determine additional structural parameters (ATKINSON [1967], VITTALI 11967]). In fact, the evaluation of shape and distribution of the bone trabecula en counters many difficulties, for a direct measurement of these features is impossible in a 2-dimensional microscopic section. Conclusions concerning these features can he drawn only with the help of auxiliary data, such as specific surface and surface