We describe a procedure for ascertaining the extent of diagenesis in archaeological human skeletons through the distribution of Sr, Ba, Cu, Pb, Fe, and Mn in cross-sections of femoral cortical bone. Element mapping is performed through Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Absolute calibrations of element concentrations were obtained using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) on adjacent dissolved bulk bone samples. By comparing a modern individual to five medieval to early modern Danish skeletons, we demonstrate the degree to which concentrations of trace elements are attributable to diagenesis. Invasion from the exterior bone surface into a degraded part of the outer cortical bone is the most frequently occurring diagenetic change. In the archaeological skeletons investigated, diagenetic modification is restricted to, at most, the outer ca. 0.5 mm of bone. In one femur, Haversian channels were filled with diagenetic material, which appears to have entered the bone through a network of cavities largely made up by Haversian and Volkmann’s canals.