To assess and substantiate the structural and metabolic mechanisms underlying the formation of intoxication, we studied the state of the pool of free plasma amino acids under the influence of sodium fluoride in the context of chronic fluoride intoxication in white rats of the Wistar population, which were orally administered sodium fluoride for 1.5 months at a dose of 20 mg / kg of body mass. Evaluation of the state of protein metabolism was conducted according to the spectrum of free plasma amino acids by ion exchange chromatography on ionites. Our studies have shown a decrease in plasma concentrations of free amino acids such as alanine, a-aminobutyric acid, threonine, serine, proline, valine, lysine, and an increase in taurine, aspartic, glutamic acid, glycine, and cysteine. The dynamics of cystine, methionine, leucine, isoleucine, cystianine, tyrosine, phenylalanine, ornithine, histidine, arginine, ammonia were not disrupted as compared with the control observation group. The decrease in the protein synthesizing function and the prevalence of catabolic processes over anabolic processes was also confirmed by the inhibition of the incorporation processes of 3H-thymidine, 3H-uridine and 14C-leucine in hepatocytes and splenocytes, which once again indicates a slowdown of synthetic processes.