Corticalhuman bone samples from three tightly dated components of a single Sicilian sitewere chemically analyzed employing the highly sensitive technique of inductivelycoupled plasma emission spectroscopy. Although the skeletons appeared to beexcellently preserved, significant diage-nesis was detected. Moreover, amajority of the elements tested showed no constant or linear variation overtime, implying that diagenetic change tends not to be a predictable function of duration of interment. Variation among major long bones of a single skeleton wasquite high, as was variation across the cortex. The latter may reflect chemicalinhomogeneity in bone tissue or may be an artifact of postmortem change. Theresults demonstrate the hazards of unsuspected and unpredictable diagenesis, which must be controlled before reliable dietary inferences can be drawn.