Ethoxyquin (EQ) has been used as an antioxidant in animal feed for many years, but pharmacological use of EQ has never been evaluated in humans despite that small amounts of EQ exist in certain food items. The level of this antioxidant in animal feeds should not be higher than 150 ppm (U.S. FDA permissions). Ethoxyquin is rapidly absorbed from gastrointestinal tract of laboratory animals like rats and mice. Peak blood concentration of the compound is observed within 1 h. Distribution of EQ in animal body is similar when it is administered orally and intravenously. Small amounts of parent EQ were detected in liver, kidney, and adipose tissue and fish muscles. It is excreted predominantly as metabolites via urine. Ethoxyquin is also registered as an antioxidant to control scald (browning) in apples and pears. EQ-induced DNA damage in human lymphocytes in a dose-dependent manner. According to the studies on dogs and laboratory animals it was shown that ethoxyquin had little acute toxicity, except when it is administered parenterally. Values of LD50 for EQ are 1700 mg kg−1 bw (rats, oral gavage), 2000 mg kg−1 bw (rats, dermal treatment, 24 h), 900 mg kg−1 bw (mice, intraperitoneal administration), and 180 mg kg−1 bw (mice, intravenous administration).