A study was made of the fluorine-ion content in the vegetables and grain grown on experimental plots of land fertilized for 4-6 years with fluorine-containing fertilizers: active slurry potassium tetrafluoroborate and sodium fluorosilicate. It was found that the fluorine-ion content in individual samples of the vegetables and grain was increased 2-32-fold as compared to that in the control samples. As for the diet, the total content of fluorine-ion was increased 6.1-12.3-fold. Experiments were made on rabbits and rats whose diets contained the vegetables and grain from the experimental plots of land. The animals of the experimental groups manifested a lowering of the prothrombin index by the end of the 6th month of the experimental studies. There was a statistically significant fall in the cholinesterase activity and an increase in the activity of glutaminopyruvic aminotransferase (by 35-42 units). The activity of total alkaline phosphatase progressively increased at the expense of the elevated activity of liver and intestinal isozymes.