Enamel F level and depth of acid etch were measured in 166 teeth from 8 communities with water F ranging from .07-5.0 ppm. Enamel F decreased progressively from the surface inward and was positively correlated with water F. Depth of acid etch was inversely related to enamel F and water F. Relationships between water F, enamel F and enamel solubility were most consistent at water F levels up to 1.0-2.0 ppm.