Introduction: The aim was to analyze intracellular oxidised glutathione (GSSG)/reduced glutathione (GSH) and serum thiol/disulfide homeostasis tests in bacterial sepsis (BS) to evaluate the contribution of oxidative stress to etiopathogenesis. Methods: A total of 92 individuals, including 49 patients and 43 healthy volunteers, were included in the present study. The cases who had high probability of BS criteria defined by Singer et al. and positive blood culture were included in the study. The intracellular oxidised and reduced glutathione and thiol/disulfide homeostasis [total thiol-native thiol-disulfide changes] tests were used in the serum samples of 49 patients. Statistical analysis was performed by comparing the results with the control group. Results: When BS and control group were compared, GSH, total glutathione (GSH+GSSG), native thiol and total thiol levels were significantly lower in BS group compared to control group (p<.001). No significant differences were detected between the two groups in terms of GSSG levels. CRP, PCT, WBC and RDW levels were significantly higher in BS group than in control group (p<.001). Conclusions: Total thiol and native thiol levels in serum and intracellular glutathione levels decreased in BS. Disrupted intracellular GSH/GSSG and serum thiol/disulfide homeostasis might have effects on BS pathogenesis by increasing oxidative stress.