Fluoride, of all inorganic substances, is among the least likely to be identified by a routine toxicological analysis. Acute poisonings with salts of hydrofluoric or fluorosilicic acid, however, although relatively uncommon, may occur. Some fluorosilicates, salts of fluorosilicic acid (e.g. Al, Zn, Pb, Mg) are used as stone consolidants, others (e.g. sodium fluorosilicate)–in the production of enamel and milk glass, or as insecticide. In this paper, two fatal cases of poisonings are presented: a suicide involving sodium fluorosilicate of a 39-year-old male who died in his flat, without hospitalization, and an accidental ingestion of zinc fluorosilicate solution (probably due to mistaking it for mineral water) by a 38-year-old male at his workplace (building), who died about 3h after ingestion of the liquid, in spite of intensive care at hospitals. Post-mortem samples were examined by the use of the spectrophotometric method with lanthanum nitrate and alizarin complexone for fluorine (after isolation of fluoride compounds by the microdiffusion method) and using a flame atomic absorption spectrometry method for zinc (after mineralization of biological material by sulfuric and nitric acids). In the first case, the results were: blood–130 µg F/ml, stomach–1150 µg F/g, small intestine content –19.6 µg F/g, kidney–56.0 µg F/g, and urine–1940 µg F/ml. In the second case, the contents of fluorine and zinc in blood and internal organs were the following: blood–6.03 µg F/ml, 23.8 µg Zn/ml; brain–1.39 µg F/g, 7.54 µg Zn/g; stomach–152 µg Zn/g; stomach content–293 µg F/g, 84.4 µg Zn/g; small intestine–37.5 µg Zn/g; small intestine content–63.4 µg F/g, 19.6 µg Zn/g; liver–9.49 µg F/g, 81.0 µg Zn/g; kidney–29.6 µg F/g, 39.2 µg Zn/g; and exceeded the normal levels of these elements in biological material many times. In addition, in stomach and liver large amounts of silica were detected. In the paper, a review of acute intoxications with various fluoride compounds (17 cases) is also presented.