An approach to the problem of bone disorders is the measurement of the skeleton’'s static and dynamic strength, an estimate of which is bone mineral density. A decrease in the latter may be due to a decrease in either Ca or P, or to dissimilar decreases in both. Consequently, the determination of the Ca/P ratio may provide a sensitive measure of bone mineral changes and may add to our understanding of the changes occurring in bone diseases. This paper reviews techniques such as transmission electron microscopy (TEM) and micro-computed tomography (μu-CT), which have been developed for thein vitroassessment of the Ca,P content and the skeletal Ca/P ratio. Their main aspects are presented, as much as results regarding the referred values. The presentation of otherin vitroorin vivotechniques, such as instrumental neutron activation analysis (INAA) or X-ray absorptiometry accordingly, would be the issue of another article. The authors argue that the choice of the best technique relies on its cost ad ease of applicability, its reliability, and precision.