The aim of this study was to see whether there would be differences in whole blood versus tibia lead concentrations over time in growing rats prenatally. Lead was given in the drinking water at 30 mg/L from the time the dams were pregnant until offspring was 28- or 60-day-old. Concentrations of lead were measured in whole blood and in tibia after 28 (28D) and 60 days (60D) in control (C) and in lead-exposed animals (Pb). Lead measurements were made by GF-AAS. There was no significant difference (P > 0.05) in the concentration of whole blood lead between Pb-28D (8.0 ± 1.1 μg/dL) and Pb-60D (7.2 ± 0.89 μg/dL), while both significantly varied (P < 0.01) from controls (0.2 μg/dL). Bone lead concentrations significantly varied between the Pb-28D (8.02 ± 1.12 μg/g) and the Pb-60D (43.3 ± 13.26 μg/g) lead-exposed groups (P < 0.01), while those exposed groups were also significantly higher (P < 0.0001) than the 28D and 60D control groups (Pb < 1 μg/g). The Pb-60D group showed a 25% decrease in tibia mass as compared to the respective control. The five times higher amount of lead found in the bone of older animals (Pb-60D versus Pb-28D), which reinforces the importance of using bone lead as an exposure biomarker.