Fluoride and its inorganic salts are widely used in industry for various purpose such as etching, metal cleaning, rust removing, etc. Fluoride ion is easily absorbed in the gastrointestinal tract after ingestion. Once fluoride has been absorbed, it interferes with metabolism and enzyme mechanisms. As a result, dysrhythmia associated with electrolyte alteration causes cardiovascular compromise, arrest and death. Herein, we report a case of fatal intoxication involving fluoride. A 67-year-old man was found groaning by his wife after drinking some unknown liquid. He was transported to a hospital emergency room and died after 90 min. General toxicological screening of the autopsy biological samples and the liquid at the scene could not reveal the presence of any toxic substance. However, analytical results by ion chromatography showed that the aqueous solution contained fluoride and ammonium ion. Thus, the quantification of fluoride was carried out in the autopsy specimens and the fluoride concentration were 61.5, 28.4 and 5,000 mg/L in heart blood, peripheral blood and gastric contents, respectively. Based on these toxicological results and autopsy findings, the cause of death was determined to be acute fatal intoxication by ingestion of the solution containing fluoride. This is the first report of the fatal case of fluoride poisoning in Korea.