Anemia is a common complication that is associated with mortality in patients with chronic kidney disease (CKD). Despite the use of erythropoiesis-stimulating agents (ESAs) to correct anemia, some patients are hyporesponsive due to the state of micro-inflammation caused by uremic toxins and hepcidin, a hormone that plays a central role in iron homeostasis. Hemodiafiltration (OL-HDF) has been associated with better clearance of uremic toxins, such as indoxyl sulfate (IS), p-cresyl sulfate (PCS) and indole acetic ascorbic (IAA) than conventional hemodialysis (HD). The aim of the study was to evaluate the effect of OL-HDF treatment on the concentration of IS, PCS, IAA, hepcidin and inflammatory biomarkers in CKD patients. Thirty-one patients (> 65 years old) incident in OL-HDF were followed for 6 months. IS, PCS, IAA, biochemical parameters, hepcidin and inflammatory cytokines were evaluated at baseline and after 6 months. We observed a significant decrease in IS and CRP plasma concentration, an increase in hemoglobin and hematocrit after 6 months of treatment with OL-HDF (p <0.05). This prospective observational study demonstrated that OL-HDF was capable to reduce IS and CRP in older patients. Whether this reduction may have an impact on clinical outcomes must be investigated in a future study.