Proceedings 2013, pp. 172-178Mycotoxins are toxins produced by fungi in many agricultural products worldwide either pre- or post-harvesting. Fusarium species are among the most researched plant pathogenic fungi (1) that produce a number of mycotoxins including DON, NIV, T-2, HT-2, fumonisins, ZEN and its metabolites α- and β-zearalenol (2). Some fungi are able to produce more than one mycotoxin, but also multiple fungi can contaminate the same crop (3). Natural co-occurrence of Fusarium mycotoxins increases the concern on the exposure to mixtures of mycotoxins e.g. co-occurrence of DON/ ZEN/ T-2/ HT-2 (4,5). Exposure to mycotoxins can result in a variety of health effects, ranging from acute toxic response to potential long-term carcinogenic and teratogenic effects (6). Effects of mycotoxins on reproduction in livestock have been reviewed extensively (7). ZEN ingestion in animals is associated with anestrus, abortion, increased embryonic and fetal death, increased stillbirths, reduced milk production, hyperestrogenism and poor quality semen (7,8) In vitro, ZEN increased the progesterone production in porcine granulosa cells (9). ZEN and α-ZOL have potent estrogenic effects and promote hormone production in H295R cells (10). DON, T-2 and HT-2 reduced cell viability, inhibit steroidogenesis and alter expression of steroidogenic genes in human adrenocarcinoma (H295R) cells (11) Leydig cells are the testicular endocrine cells capable of producing steroid hormones. Pig Leydig cell culture is a good in vitro model to study steroidogenesis and screen effects of some chemicals (12,13). We hypothesize that F. graminearum culture extracts contain a mixture of naturally co-occurring mycotoxins that are able to cause deleterious effects in vitro in Leydig cells.