Cytokine dysregulation is an important factor underlying the immune unresponsiveness to hepatitis B vaccination (HBV) in renal transplant recipients. This study investigated the relationship between monocyte-derived interleukin-6 (IL-6) and interleukin-10 (IL-10) production and the immune responsiveness using flow cytometry (cytoflow) after whole blood culture. According to their previous response to hepatitis B vaccination, 40 renal transplant recipients were divided into two groups of 20 patients. The percentage of CD 14+ monocytes stained positive for intracellular IL-6 or IL-10 was measured using flow cytometry after 4 and 20 h of whole blood culture with lipopolysaccharide stimulation. The percentage of CD 14+/IL-6+ cells after incubation in vitro for 4 h was lower in the responders compared to the non-responders and controls (27.15+/-8.93 vs 35.47+/-9.95, P=NS; and 37.06+/-10.89, P<0.05 respectively). The staining intensity of IL-6 at 4 h for responders was also significantly reduced. At 20 h, there were a significantly higher percentage of CD 14+/IL-10+ positive cells in the responders compared to the non-responders (41.87+/-18.39 vs 27.55+/-17.25, P<0.05). These results indicate that alteration of intracellular cytokine profile in activated monocytes distinguishes the HBV vaccination responders from the non-responders among renal transplant recipients. The capacity to upregulate monocyte IL-10 production in this subset of patients may modulate the immune responsiveness and effectively assists in mounting a positive response to HBV vaccination.