When septic multiple organ dysfunction syndrome (MODS) occurs as a result of endotoxemia, diverse chemical mediators are excessively produced, and the patient becomes seriously ill. Under such circumstances, it is difficult to improve the patient's condition by endotoxin apheresis alone and hemodiafiltration should be carried out to remove excessive chemical mediators. Series-parallel treatment combining continuous endotoxin apheresis and hemodiafiltration is recommended for patients with septic MODS.