The aim of the present study was to define a methodological strategy for understanding how post- mortem degradation in bones caused by the environment affects different skeletal parts and for selecting better preserved bone samples employing rare earth elements (REEs) analysis and multivariate statistics. It is the first time that REEs are used to evaluate diagenesis impact in archaeological bones. To test our methodological proposal the samples selected belong to adult and young individuals and were obtained from the late-ancient roman necropolis of the c / En Gil (35 samples), located in the downtown area of ?? Valencia City. Therefore, a method for the determination of major elements, trace elements and REEs in bone remains has been developed employing Inductively-Coupled Plasma – Optical Emission Spectroscopy (ICP-OES). Bone samples, mainly rib and femur, from 8 individuals have been studied. Principal Component Analysis (PCA) was employed to facilitate the interpretation of the results. Zn/Ca and Sr/Ca parameters show that diet profiles of a population could change depending on the class of bones analyzed.