The aim of this study was to validate 109Cd-based K-shell x-ray fluorescence measurements against atomic absorption spectrometry (AAS) measurements of core and surface tibia lead. The lead content of nine adult human cadaver tibiae was measured using 109Cd-based K-shell x-ray fluorescence (XRF) spectrometry and the results compared to measurements obtained using electrothermal atomization atomic absorption spectrometry following acid digestion. Each tibia was divided into nine cross-sectional segments, which were further separated into tibia core and surface samples for the AAS analytical measurements. Proximal-distal variability in tibia lead concentration as determined by AAS was previously described for both surface and core segments and was found to decrease towards the ends of the tibia, in contrast to XRF in which lead was found to increase towards the tibia ends. The effect of this contrasting behaviour on the agreement between XRF and AAS measurements was examined. Lead concentrations determined by AAS ranged from 3 to 19 microg of lead per gram of dry weight bone (microg g(-1)) for tibia core and from 5 to 32 microg g(-1) for tibia surface. Lead concentrations determined by XRF ranged from 2 to 35 microg g(-1) dry weight. No statistically significant difference was found between mean XRF-measured concentrations and mean surface lead concentrations measured by AAS, but XRF significantly overestimated tibia core lead concentrations by between 5 and 8 microg g(-1).