To test for the presence of a cariostatic agent the cariogenicity of cooked and uncooked home-prepared maize, factory-milled maize and factory-milled sorghum was compared to cooked wheat starch and sucrose, and to maize plus sucrose and sorghum plus sucrose, using a rat caries model. Comparison of test groups to control groups indicated that the model system worked well. Maize and sorghum, whether cooked or uncooked, had a low cariogenicity but this was increased by the addition of 20% sucrose. The results of the investigation did not support the presence of a cariostatic agent in maize and sorghum.