Rats were given diets containing different amounts of calcium, phosphorus and lead. 2. Pb retention was greatly increased when the diets contained less Ca or P than the minimum estimated requirement of the rat. 3. The release of Pb already incorporated into the skeleton was inhibited by diets low in Ca but was not affected by diets low in P. 4. The retention of Pb given intraperitoneally was not affected by dietary Ca or P. 5. It can be concluded that dietary Ca and P influence the absorption of Pb by the gut and dietary Ca influences the metabolism of Pb in the bone. 6. There were changes in the distribution of Pb among the tissues due to changes of dietary Ca. 7. At low body concentrations, Pb probably affected skeletal growth.
