Abstract: Inflammatory reactions that result from microbial infections, both localized and systemic, are reported to cause transient or permanent male infertility. The cellular mechanisms underlying the inhibitory effect of microbial infection on spermatogenesis is not fully understood. However, there is evidence that spermatogenesis is affected by bacterial lipopolysaccharides (LPS) that induce acute inflammatory responses. The aim here was to use LPS treatments to investigate the potential oxidative stress and toxicity in primary cultures of adult rat Sertoli cells. The Sertoli cells were established and incubated with different concentrations of LPS (5, 10 or 20μg/ml) for 6, 12 and 24h. Lipid peroxidation (LPO) and hydrogen peroxide (H2O2) production, along with superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione-S-transferase (GST), glutathione reductase (GR), reduced glutathione (GSH), lactate, lactic acid dehydrogenase (LDH), γ-glutamyl transpeptidase (γ-GT) and β-glucuronidase were measured in these cells. LPO as well as H2O2 production were significantly increased while antioxidant enzyme activities and GSH concentration were significantly depressed. Effects were dose and time-dependent at all incubation periods with 10 and 20μg/ml LPS. Moreover, markers of Sertoli cell function such as lactate production, LDH, γ-GT and β-glucuronidase activities were decreased in a time and dose-dependent manner. Incubation of Sertoli cells with 5μg/ml LPS for 12 and 24h significantly increased oxidative status but significantly decreased the antioxidant enzyme activities, GSH concentration and Sertoli cell markers. In contrast, the oxidative and antioxidant status and markers of Sertoli cell function did not show any significant change in treated Sertoli cells with 5μg/ml LPS for 6h. Therefore, it may be concluded that LPS induces oxidative stress in Sertoli cells and adversely affects Sertoli cell functions. [Copyright &y& Elsevier]