Concentrations of strontium (Sr) were given preeruptively to rats at 0.0, 0.5, 1.0, 2.5, 5.0, and 7.5 μg Sr/10 g body weight by esophageal intubation. At weaning, the same rats were given 0, 5, 10, 25, 50, and 75 mg Sr/liter via the drinking water. Caries scores were recorded for buccolingual, morsal, sulcal, and proximal lesions in all rats. Reductions in caries scores were only seen for buccolingual scores. Maximum reductions in buccolingual scores were found in rats given 7.5 μg Sr/10 g body weight preeruptively and 75 mg Sr/liter posteruptively. Uptake of strontium by enamel was significantly correlated with drinking water concentration