Zearalenone (ZEA) is a nonsteroidal estrogenic mycotoxin produced by several Fusarium fungi, which are regular contaminants of cereal crops worldwide [1-4], causing economic losses and alterations on animal and human health [5-7]. Research has focused on estrogenic effects in domestic animal species, some recent studies showed that ZEA causes immunological alterations in several biological models. ZEA decreased the expression of CD3⁺, CD4⁺, CD8⁺ and CD56⁺ peripheral blood lymphocytes and caused chromosomal aberrations in bone marrow of Balb/c mice [8,9]. In addition, ZEA affect the expression of chicken splenic lymphocytes cytokines (IL-2, IL-6 and IFN-g) at the mRNA level [10], and inhibit the mitogen stimulated proliferation of bovine peripheral blood mononuclear cells in vitro [11]. Although the effect of ZEA on the human immune system is not fully understood, ZEA decreased proliferation of lymphocyte [12], and mononuclear cells [13]. Besides, ZEA and other mycotoxins induced immunosuppression of NK cells activity and slightly inhibited antibody dependent cellular cytotoxic reaction [14]. Also, ZEA induced macromolecules synthesis and stress response in different cultured such as Caco-2 cells [15,16] and HepG2 cells [17,18]. In this way, there is not enough information about acute toxic effects in the case of human leukocytes. In particular, we evaluated cytotoxic and lipid peroxidation activities induced by ZEA in concentrations of 10 to 80 μg/mL.