The main arguments, discussed by different international organizations, which confirm the significance of problems connected with the presence of zearalenone in animal feed materials and their influence on the safety of food materials are shown in this review article. The main world research trends focused on zearalenone, as undesirable substances, are also presented. A variety of Fusarium fungi produce a number of different mycotoxins, for example zearalenone. Is not true that Fusarium fungi are they the most prevalent toxin-producing fungi only in the northern temperate regions, are also commonly found on cereals grown in the temperate regions of America, Europe and Asia. Zearalenone have been shown to cause a variety of toxic effects in both experimental animals and livestock, and have also been suspected of causing toxicity in humans. Zearalenone is a stable compound, both during storage/milling and the processing/cooking of food, and it does not degrade at high temperatures. Studies of metabolism indicate that zearalenone is fairly rapidly absorbed following oral administration, with the formation of alpha- and beta-zearalenol and alpha- and alpha-zearalanol, which are subsequently conjugated with glucuronic acid. This mycotoxin and some of these metabolites have been shown to competitively bind to estrogen receptors in a number of in vitro systems. Binding to specific receptors has been demonstrated in the uterus, mammary gland, liver and hypothalamus of different species. Additionaly alterations of immunological parameters were found at high zearalenone concentrations in vitro. Zearalenone causes alterations in the reproductive tract of laboratory animals and domestic animals. Various estrogenic effects such as decreased fertility, increased embryolethal resorptions, reduced litter size, changed weight of adrenal, thyroid and pituitary glands and change in serum levels of progesterone and estradiol have been observed, and teratogenic effects were found in pigs and sheep. It may be that the safety of zearalenone could be evaluated on the basis of the dose which had no hormonal effects in pigs, the most sensitive species, and a temporary Tolerable Daily Intake for zearalenone of 0.2 microgram/kg of body weight, could be established.