The role of the vagus nerve in controlling and modulating inflammatory responses under physiological conditions has been investigated. The purpose of this study is to assess changes in the immunological state evoked by vagus nerve stimulation in humans, by measuring cytokines produced by peripheral blood mononuclear cells (PBMC). We compared induction of IL-1beta, IL-6, IL-8, IL-10 and TNF-alpha by lipopolysaccharide (LPS)-stimulated PBMC which were isolated from patients treated with vagus nerve stimulation for refractory epilepsy. We observed a significant decrease in IL-8 induction by LPS-stimulated PBMC after 6 months of vagus nerve stimulation in comparison to the pre-stimulation state. No significant changes were seen in the induction of IL-1beta, TNF-alpha, IL-6 or IL-10. The present study shows that cytokine induction by PBMC isolated from patients with refractory epilepsy is altered by long-term vagus nerve stimulation.